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2010, 29 (S1): -0 doi:
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RESEARCH ON CHARACTERISTICS OF HIGH-TEMPERATURE AND
CONTROL OF HEAT-HARM OF SANHEJIAN COAL MINE

HE Manchao1，2，GUO Pingye1，CHEN Xueqian1，MENG Li1，ZHU Yanyan1

2010, 29 (S1): -2597 doi:
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The heat harm is even worse with the increase of mining depth in geothermal-abnormal coal mine. Based on the analyses of geothermal field，geothermal gradient changes and rock thermal physical properties of Sanhejian coal mine，it is revealed that geothermal value suddenly increases and the heat flow values become high with the mining depth increasing，and Sanhejian coal mine is a typical geothermal-abnormal coal mine. Lacking of cold source and abnomal geothermal value is the characteristics of Sanhejian heat harm mode. Focused on the characteristics of Sanhejian heat harm mode，combined with the ground heating problems，a new heat harm control technology，which is named as HEMS(high temperature exchange machinery system) of Sanhejian mode，is proposed. This technology which untilizes the underground heat water to provide upperground heating，has a cold storage in the Quaternary underground storage layer for cooling，the heat harm is resolved and upperground heating is realize at the same time. The first phase of HEAMS is realized in Sanhejian coal mine. Through the cooling effect analysis of working face 72201，the result shows that the working environment of high temperature and high humidity is improved significantly. This heat harm control technology is worth to be applied and popularized in deep mining and related fields.

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METICULOUS DESCRIPTION OF JOINTED ROCK AND BLOCK STABILITY ANALYSIS OF SURROUNDING ROCK OF SUPER-LARGE SECTION MULTI-ARCH TUNNEL

XIA Caichu1，2，CHEN Xiaoxiang1，2，3，XU Chongbang1，2，ZHAO Xu1，2

2010, 29 (S1): -2603 doi:
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Jinjishan tunnel in project of Fuzhou airport expressway construction is multi-arch tunnel with eight lanes in China. In surrounding rock of the tunnel，joints were developed which cut the original rock blocks into even smaller blocks. The blocks can be easily disturbed and become unstable during tunnel excavation. To keep the blocks stable is one of the most important problems in construction of the highway tunnel. Data of joints unveiled during excavation in several cross-sections of mid-drift of the tunnel and other areas are collected in detail and described meticulously. Based on statistical analysis of the data，distribution of joints in whole face tunnel relative to the same cross-section is forecasted. The block theory is adopted to study the location，volume，sliding force，safety factor and other parameters of key blocks in the cross-sections of whole face tunnel. Mechanical calculations of stability are performed to analyze the key blocks in different situations which are the none of reinforced situation，reinforced by anchors situation，and reinforced by anchors and shotcrete situation. The situations are evaluated and advices are made for the engineering application of the tunnel.

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TEST ON STRUCTURAL PROPERTY AND APPLICATION OF CONCRETE-FILLED STEEL TUBE SUPPORT OF DEEP MINE AND SOFT ROCK ROADWAY

GAO Yanfa1，2，WANG Bo1，2，WANG Jun1，2，LI Bing1，2，XING Fei1，2，WANG Zhonggang3，JIN Tongle3

2010, 29 (S1): -2609 doi:
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Traditional supports are difficult to maintain the route work of roadway in deep well due to dynamic pressure propagation within soft rock. To tackle this problem，concrete-filled steel tube support is developed；and further the mechanical properties of the support are tested in laboratory. The experimental supports are composed by four sections of f140 mm×4.5 mm steel tube，with concrete C40，and joints with casing linkage. Under the conditions of lateral constraint and vertical point load pressure，the ultimate bearing capacity of experimental support is about 1 504.1 kN；and the vertical ultimate compressive deformation reaches 82.65 mm，resulting in failure mode of steel tube. Compared with the U-shaped steel support，concrete-filled steel tube support holds not only high supporting capacity，but also with a competitive price. So concrete-filled steel tube structure may have an extensive application to coal mine roadway.

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INFLUENCES OF LOADING RATES ON MECHANICAL BEHAVIORS OF ROCK MATERIALS

YIN Xiaotao1，2，GE Xiurun1，LI Chunguang1，WANG Shuilin1

2010, 29 (S1): -2615 doi:
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[PDF 430 KB] (2008)

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Loading rates can result in the change of rock¢s rupture shape. There is a critical velocity during the breakage process of material when plasticity transferring to brittleness. The numerical sample of rock is virtually performed by compiling program through embedded Fish language under particle flow code condition. Then，uniaixal compression tests with four kinds of loading rates，i.e. 0.000 5，0.001 0，0.005 0，0.050 0 m/s，are designed to study the loading rate effect. Moreover，the influences of rupture process，crack number and propagation，stress-strain curve，stress and strain，energy transformation done by loading rate are analyzed based on these tests. It is found that increase of loading rate ruins the advantageous shear zone¢s development，which makes the shear zone expanding with same velocity；and the material failure surface appears cone shape，in which the loading rate enhances the mechanical and deformation features of material at meso-scale，which makes the rock breaking into pieces；and that the rate causes energy loss increasingly，which is relevant to the ability of absorbing and dissipating energy from its mechanical behaviors.

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STABILITY ANALYSIS OF INSULATING PILLAR OF EXCAVATION OF CHAMBISHI COPPER MINE IN DEPTH

ZHAO Xingdong

2010, 29 (S1): -2622 doi:
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The appropriate size and stability of insulating pillar，which are transition stretch shifting from shallow excavation to deep mining，are very important for safe production of deep mine. According to the field engineering condition shifting from shallow excavation to deep mining，the appropriate size of insulating pillar is calculated and analyzed by using methods of limit span mechanism，empirical equation method and limit equilibrium method. The analysis result shows that for guaranteeing the insulating pillar stability the thickness of insulating pillar is 21 m. According to insulating pillar with thickness of 21 m，original design scheme is revised. FLAC3D is adopted to analyze the stability of revised design scheme，deformation and failure process of insulating pillar during caving. The numerical result shows that when mine is excavated 33 m high under insulating pillar，the insulating pillar will lose its strength and fail. Meanwhile，thickness of 28 m overburden layer is safe for non-hollow sublevel caving，which can guarantee the safety of personnel and equipment. It validates the revised insulating pillar thickness and conducts the production，which will supply the empirical method for the similar mine.

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BOREHOLE EXPLORING RESEARCHES ON ZONAL DISINTEGRATION OF ROOF STRATA WITH LATERAL CAVE IN DEEP MINE

TAN Yunliang1，SUN Chunjiang1，2，NING Jianguo1，LI Haitao1

2010, 29 (S1): -2629 doi:
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Strata exploring instrument of YTJ20 was adopted for inspecting the zonal fractures inside roof strata with lateral cave，in eastern ventilation roadway No. 2222 of 1 300 m deep in Suncun mine. The results show that high level stress is the root of zonal disintegration in deep mines. Under the lateral cave condition，the quantity of fractured zones inside the high stress strata is more than that inside the meiobar of strata being in the state of unloading and large subsidence. But tensile fractures expand underneath the wide split or separation in the unloading and large subsiding strata，so the location of large-scale zonal disintegration can be determined by measuring the bedding separation. Also，the mechanical properties of strata have a great influence on the zonal disintegration；zonal disintegration is easier to occur in siltstone than in sandstone. The results supply a basis for researching the structure and mechanical features of deep key strata；and establishing the relations between zonal disintegration and rationale of rock mechanical disaster in deep mine further is also presented.

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ANALYSIS OF HORIZONTAL STRESS FIELD AND FAR FIELD MOVEMENTS DUE TO DEEP MINING

LI Wenxiu，MENG Qingli，WEN Lei，LIU Xiaomin，LIU Lin

2010, 29 (S1): -2636 doi:
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Guanzhuang iron mine is one of a number of underground iron mines in the Eastern China，which is at depths of 500–1 000 m using the pillarless sublevel caving method. Stress measurements confirmed that，in Guanzhuang iron mine，the magnitude of the maximum horizontal stresses is typically 1.14 times greater than that of vertical stresses. The north mining area is at depths of 510–550 m，and movements are being measured 500 m or more far away from an active sublevel. Horizontal displacement figure shows one example of these measured movements and it can be seen that，in this case，lateral movements of about 50 mm were measured about 500 m away from a sublevel panel being extracted at a depth of about 510 m. There are no measurable vertical movements at this distance. Horizontal displacements due to underground mining are analysed by using the stochastic medium and numerical method. These lateral displacements have been termed as far field movements. It has become apparent that the far-field movements are due to redistribution of the high horizontal stress field in the sandstones and siltstones that overlie the Guanzhuang iron-seams.

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A PRACTICAL METHOD TO SIMULATE THICKNESS OF WEAK INTERBED AND ITS APPLICATION

ZHANG Zhiqiang1，2，LI Ning1，CHEN Fangfang3，SWOBODA G4

2010, 29 (S1): -2644 doi:
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Such discontinuities as weak interbeds，faults，joint distributed in surrounding rock mass play an important and decisive role in the stability of surrounding rocks of underground openings and the safety of supporting system in most practical engineering cases. Based on the equal deformation and strength for discontinuities，a method is presented，which can be applied to simulate the thickness of weak interbed in the numerical test with unique FEM mesh；and its validity，reasonableness and practicability are validated via some numerical tests. This method is composed by the COJO element，which is a perfect element formed in geotechnical FEM software FINAL to simulate the properties of contact，and influenced zone of interbed that is a fine mesh zone with constant thickness in FEM mesh. In this method，The mechanical parameters for influenced element are altered in order to reflect the various thicknesses of faults. Based on this method，systematic numerical tests have been conducted to study the stability of a tunnel surrounded by different thickness weak interbed buried in surrounding rock mass and the safety of supporting structures. These different thickness weak interbeds are with the thicknesses of 0D，0.005D，0.010D，0.020D，0.200D，respectively，where D is span of underground opening；and the surrounding rock masses are graded in classes II，III，IV. Some qualitative and quantitive laws on the influence of weak interbeds with different thicknesses are summarized，especially the influences on the deformation，stress of surrounding rock mass，as well as the inner force of shotcrete supporting structure. These results may have reference and guide significance to the selection of location and layout of underground opening，the design of supporting system and the construction of underground openings，especially these tunnels stroken to the faults.

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RESEARCH ON DETECTION OF LOW RESISTIVITY INTERBED IN FRONT OF TUNNEL FACE BY MEANS OF TRANSIENT ELECTROMAGNETIC METHOD

SU Maoxin1，LI Shucai1，XUE Yiguo1，LI Xiu2，ZHANG Qingsong1

2010, 29 (S1): -2650 doi:
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[PDF 344 KB] (920)

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Practices show that the unfavorable geological body with water or mud in front of the tunnel face is great dangerous to the tunnel construction. If these unfavorable geologic bodies can not be detected，which will effect the tunnel construction progress；moreover，some engineering accidents and casualties may happen. As the transient electromagnetic method(TEM) is sensitive to the low resistivity body，and the unfavorable geological bodies usually can be equal to a low resistivity interbed，the study of the detection of the low resistivity interbed in front of the tunnel face becomes very meaningful. The TEM-equivalent conductive plane method based on the whole space theory and the apparent longitudinal conductance and its differential coefficient imaging will be used to have a forward modeling and application research on the detection of the low resistivity interbed in front of the tunnel face. Besides，a discussion on the electricity interface response character of the apparent longitudinal conductance is presented with differential coefficient imaging and the interpretation combined with apparent resistivity section contours. At last，some characteristics and laws of the detection are summed up so as to guide the actual TEM tunnel geological forecast and improve TEM detection accuracy and precision.

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SAFETY EVALUATION OF TUNNEL LINING WITH LONGITUDINAL CRACKS AND REINFORCEMENT DESIGN

WANG Hualao1，2，LIU Xuezeng3，LI Ning1，XIE Dongwu3

2010, 29 (S1): -2656 doi:
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Crack is one of the major diseases of the tunnel lining in the operation phase，especially the arch longitudinal cracks are more hazardous to the bearing capacity of the original lining. Through the evaluation criterion of crack，the safety of lining with longitudinal crack was evaluated；and the safety level was proposed. Meanwhile，the stiffness degeneration model was used to evaluate the bearing capacity of the original lining；and the structure safety coefficient was calculated before lining reinforcement. Engineering case study shows that the stiffness degeneration model to evaluate the capacity of lining is feasible，which provides an important basis for the reinforcement of the tunnel，as well as a new reasonable method for the safety evaluation of the lining with longitudinal cracks，the bearing capacity calculation，and the reinforcement designing.

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EXPERIMENTAL STUDY OF MECHANICAL PROPERTIES OF WATER-SATURATED WEAKEN SHALE IN GONGHE TUNNEL

TENG Hongwei1，REN Song1，JIANG Deyi1，YANG Chunhe1，2

2010, 29 (S1): -2662 doi:
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[PDF 315 KB] (906)

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The geological condition of Gonghe tunnel of Chongqing—Changsha highway is very complex. There are many difficulties when the tunnel is being constructed. There are many vertical cracks in the primary support after the tunnel is excavated. The surrounding rock of the cracking position is shale，which is easily weathered，and strong hydrophilic and water-softening have identified beddings and joints. All these characteristics have an important impact on the primary support and the long-term stability of the tunnel. At first，the basic mechanical parameters of the shale are gotten from the basic mechanical test of the shale. And then，the water-saturated softening experiment of the shale is carried out with the combination of sound wave test and uniaxial compression test，and the water-saturated softening equations of the shale are obtained. The test results show that both strength and elastic mould are low；the strength and elastic modulus will be lower in the process of water-saturated time，which meets the rule of a negative exponential function，and can agree well the actual water-saturated softening rule of the shale. The combination of sound wave test and uniaxial compression test can significantly reduce the need of rock samples，and also can improve test accuracy. The research achievements provide the basic parameters for re-designing the primary support structure and analyzing the long-term stability of the tunnel lining structure.

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SAFETY ASSESSMENT MODEL OF METRO EPB SHIELD TUNNEL CONSTRUCTION

YOU Pengfei，MOU Ruifang

2010, 29 (S1): -2668 doi:
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[PDF 187 KB] (818)

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For the characteristics of metro earch pressure balance(EPB) shield tunnel construction，first of all，the risk factors of shield tunnel construction by using the idea of system engineering are identified，and its levels are analyzed，and safety assessment index system is structured. Then the weights of indicators and criteria layer are determined by functional theory. Using SCL and LEC to assess items of guide line layer，carrying out risk levels of the target and guide line layer，using fuzzy comprehensive assessment theory to assess risk level of guide line layer to reach the risk level of the target，these are used to form a safety assessment model，which can provide reference for similar projects construction.

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RESERVED DISPLACEMENTS FOR ANTI-CRACK DESIGN OF METRO TUNNEL PASSING THROUGH ACTIVE GROUND FISSURE ZONES

HUANG Qiangbing1，2，PENG Jianbing1，2，WANG Qiyao3，GAO Huyan4

2010, 29 (S1): -2675 doi:
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[PDF 633 KB] (815)

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Xi¢an metro under construction pass through many ground fissure active zones，the future large deformations of active ground fissure zones make a serious threat on Xi¢an metro tunnel. The genesis，moving mode and profile characteristics of active ground fissures in Xi¢an are analyzed，the active tendency and maximum vertical displacements of active ground fissures in the design life time of metro tunnel are estimated. The behaviors of metro tunnel passing through active ground fissure are studied with three-dimensional FEM，the results show that tunnel lining appears cracks when the vertical displacement of ground fissure increases to 20 cm，structural measures such as setting up seams in tunnel segmentation，adding flexible joints between segmented tunnel and enlarging tunnel lining cross-section should be adopted in structural design of metro tunnel passing through active ground fissure zones. Based on the deformation characteristics of active ground fissures and numerical simulation results，the three-dimensional moving model of metro tunnel which is perpendicular and oblique to active ground fissure zones，is respectively established，the reserved value of vertical，transverse and axial displacements for metro tunnel in design are calculated. The conclusions can be presented as the reference for lining structure design of tunnel passing through the ground fissure active zones.

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STUDY OF MACRO STRESS SHELL EVOLVING CHARACTERISTICS OF ROCK SURROUNDING FACE

XIE Guangxiang，YANG Ke

2010, 29 (S1): -2680 doi:
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A key issue in underground mining is to understand and master the evolving patterns of mining-induced stress，especially abutment pressure，and to control and utilize the action of rock pressure. Based on the mechanical characteristics analyses of macro stress shell(MSS)，in-situ observation，numerical and physical modeling tests have been carried out to investigate the redistribution patterns，mechanical characteristics and geometrical parameters of the MSS developing and those correlations in the rock surrounding a fully mechanized top-coal caving (FMTC) face with unsymmetrical disposal. The results show that，with the face advancing，the MSS evolution is bundled of mined-induced high stress developing and recurrently equilibrating process until one new balance forming and the MSS development shape is an approximate half-space ellipsoid shell in overburden strata. The mechanical characteristics of MSS evolution are opened out and the MSS development could be divided into three stages in unsymmetrical disposal with small wide coal pillar，namely the old MSS expanding stage，the new MSS forming stage，and the gradually-correspondingly stabilizing stage. Drastic rock pressure in mine may occur when the balance of the stress shell is destruction or the forces system of the stress shell transfers. This study will pay an active role in theoretic references to rocks stability control，gateway layout，efficiency and safety mining.

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MULTI-SCALE AND ANISOTROPIC CHARACTERIZATION OF COAL STRUCTURE BASED ON SEM IMAGE ANALYSIS

GONG Weili1，2，LI Chen1，2

2010, 29 (S1): -2689 doi:
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Non-transparency of microstructures for the porous media has long been the obstacle for a deep understanding of the mechanisms of rock damage and coal and rock outbursts at depth. As an attempt，a methodology based on wavelet multi-resolution analysis(MRA) for visualization and multiscale-anisotropic-detailed characterization of pore space for complex porous media at meso- and microscopic scales is proposed. In order to validate the proposed approach，observations are made on the six groups of coal rock specimens by using scanning electron microscope(SEM)，sampled from six different underground mining districts；the integrated image processing schemes are conducted for the so called“sub-pixel”scale analysis of the resulting SEM images，including multi-scale wavelet transform，image segmentation and reconstruction. The detail sub-bands coefficients of the wavelet transform are used to reconstruct images of the horizontal，vertical and diagonal dominant micropores of the microporous matrix. In addition，the probability density distribution of the characteristic length for the pore throat and cavity，the porosity and fractal dimensions for the pores at multiple scales are calculated. The segmented macro-fractures by the MRA are at micron scale while the micro-pores are at nano-scale. The macro-fractures of all the specimens have much larger fractal dimension value than that of the micro-pores. The profiles of the pore throat distribution for all the specimens take on the shape of single peak，and the peak value is the measure of the drag forces for the fluid transport，whereas the curves of the pore cavity take on the shapes of single or multiple peaks，and the maximal peak value represents the storage capacity for the fluids. The obtained results validate the applicability of the microscopic image based approach for characterization of the geometrical boundary and structural features of fractured rocks，which will certainly contribute to a deep understanding of the influences of the complex pore structures on the nonlinear behaviour of the rock masses at depth.

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STUDY OF BLOCK-DISCRETE-SPRING METHOD BASED ON CONTINUUM MECHANICS

FENG Chun1，LI Shihai1，YAO Zaixing1，2

2010, 29 (S1): -2704 doi:
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[PDF 854 KB] (893)

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A block-discrete-spring method based on continuum mechanics is presented and this method would be applied to simulate the progressive failure of geological body. The theoretical basis of this approach is continuum mechanics and the discrete object is regular hexahedron with 8 nodes. According to shape function theory of FEM and element stiffness matrix of regular hexahedron，12 edge springs are obtained，and the formula，spring stiffness，related displacement and physical meaning of each spring are presented. The elastic result achieved with this method is the same as that of traditional FEM，and on this basis，Mohr-Coulomb criterion and tensile criterion are introduced to calculate the failure of spring. If all springs in the block are broken，the block is treated as particles. Double judgement model is adopted to estimate the failure of block. The purpose of block failure judgement is to choose the potential failure plane for springs，while spring failure judgement is used to calculate the real spring force. Finally，the rationality of the failure result calculated by block-discrete-spring method is approved by some cases. The essence of block-discrete-spring method is to transfer the element of the traditional FEM to structure according to the 12 springs，by which，the inner failure character of block and the progressive failure process of geological body could be studied by analyzing the failure of springs.

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STUDY AND PREDICTION OF SURFACE SUBSIDENCE OF SALT ROCK CAVES USED FOR GAS STORAGES IN JINTAN SALT MINE

QU Dan¢an1，2，YANG Chunhe1，3，REN Song1

2010, 29 (S1): -2711 doi:
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[PDF 487 KB] (957)

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The salt rock caves used for gas storages in Jintan salt mine are the important auxiliary engineering of West-East Gas Transmission. It¢s used for gas peak shaving and ensures the safety of supplying gas in the Yangtze River Delta. The accurately predicting the surface subsidence is the important method for ensuring the safety of the gas storages. Based on the rule of the transferring if one terrane by one terrane，the surface subsidence caused by the shrinking of salt rock caves in 20 years and the surface subsidence caused by the collapse of salt rock caves are predicted by the new probability integral 3D model. Then the time factor of the surface subsidence of the Jintan salt mine is obtained by the dynamic forecasting model and the surface subsidence can be achieved. The predicted value is very close to the measurement value，which proves that the transfer model has more forecasting precision.

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EXPERIMENTAL STUDY OF FULL PROCESS OF STRAIN OF ROCK SALT AND SALT-MUDSTONE INTERLAYER IN HUAI¢AN SALT MINE

TANG Mingming1，WANG Zhiyin1，DING Guosheng2

2010, 29 (S1): -2719 doi:
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For investigation on the mechanical characteristics of layered salt rocks in Huai¢an Salt Mine，Jiangsu Province，and in consideration of the laminative geological structural character of most salt mines in China，experimental studies of uniaxial and triaxial compressions are carried out on three kinds of rock samples which are rock salt，mudstone and salt-mudstone interlayer. The experiment results indicate that：(1) The strain-stress relationship of rock salt and salt-mudstone interlayer under uniaxial compression or triaxial compression performs obviously strain hardening-softening properties. (2) The rock salt and salt-mudstone interlayer have obvious plastic deformation ability. The elastic modulus measured by the cycle loading-unloading curve is better than that measured directly from the primeval loading curve. (3) For the rock salt，the cohesive force is getting smaller and smaller while the internal friction angle first increases and then decreases with the plastic shear deformation increasing. (4) The presence of mudstone interlayer affects the mechanical characteristics of samples remarkably. The primary phenomenon is the strength¢s increasing. The failure modes of the mudstone interlayer rock salt are determined by their states.

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APPLICATION OF UNASCERTAINED MEASUREMENT MODEL TO PREDICTION OF CLASSIFICATION OF ROCKBURST INTENSITY

SHI Xiuzhi1，ZHOU Jian1，DONG Lei1，HU Haiyan1，WANG Huaiyong1，2，CHEN Shouru1

2010, 29 (S1): -2726 doi:
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Based on the unascertained measurement theory and the actual characteristics of the project，an unascertained measurement classifying model to predict the possibility and classification of rockburst is established. Firstly，the main factors of rockburst，such as the maximum tangential stress of the cavern wall sθ，uniaxial compressive strength sc，uniaxial tensile strength st，and the elastic energy index of rock Wet，are taken into account in the analysis. Three factors，the stress coefficient of rock sθ/sc，the brittleness coefficient of rock sc/st and the elastic energy index of rock Wet are taken into account from the aspects of the causes of rockburst and its characteristics in the analysis，according to the unascertained factors of classification prediction of rockburst. Then the unascertained measurement function is obtained based on the initial data for the analysis of the rockburst of eighteen rock projects around the world. The problems of uncertain factors in classification prediction of rockburst are solved by qualitative analysis. The index weights of all factors are calculated using entropy theory. Finally，the evaluation results of the prediction and classification of rockburst are obtained on the basis of the rule of incredible recognition. It indicates that the unascertained measurement assessment results agree well with the actual records，and are consistent with those of the fuzzy synthetic evaluation method，the attribute synthetic evalution method，the grey optimization model and the matter-elements method. Therefore，the feasibility of the proposed model is validated. Furthermore，a case of Qinling tunnel is analyzed by using the proposed method in order to study the effectiveness and feasibility of the model. The results show that the prediction results agree well with the practical records，which prove that the unascertained measurement model is effective and available，and can be applied to the prediction for the possibility and classification of rockburst in underground engineering.

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RESEARCH AND APPLICATION OF CORRELATION BETWEEN DEFORMATION MODULUS AND WAVE VELOCITY OF ROCK MASS IN HYDROELECTRIC PROJECT

LI Weishu1，2，HUANG Zhipeng1，2，TAN Xin1，2

2010, 29 (S1): -2733 doi:
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[PDF 263 KB] (896)

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It¢s generally to determine deformation properties of large-scale and deep rock mass by the relationship between compression wave velocity(VP) and deformation modulus(E0) of rocks obtained by bearing plate test in hydroelectric project. The relation between E0 and VP is related to the representation of geological subjects，test number，test methods and the selected function，relationship between E0 and VP. The impact to deformation properties is studied，which comes from four aspects of the test number：geological representation，experimental conditions，and function relations. Taking typical projects as examples，the features and general rules of the E0-VP relationships established by more than 10 domestic hydroelectric projects are analyzed. The result shows that the established relationship between E0 and VP has certain universality and applicability subjected to the consideration of main factors，which has very important significance for evaluating deformation parameters of wide range rock mass and deep rock mass in different exploration phases.

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STUDY OF FATIGUE PROPERTIES AND CRITICAL STRESS MEASUREMENT METHOD OF ROCK

FENG Chunlin1，WU Yongfeng2，FENG Fuxian1

2010, 29 (S1): -2740 doi:
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[PDF 278 KB] (930)

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For seeking a solution to solve of the discreteness of rock parameters，on the basis of the testing results of uniaxial compression，fatigue deformation properties of granite and white sandstone，a new measurement method of the critical stress of rock is put forward. The method is first based on the different peak stress-stain curves，which is grouped，and then fatigue testing is performed at different heights，at low stress levels. According to testing results，steady and unsteady state curves can be drawn and both curves crossover point is found. Its two important parameters，i.e. stress and strain，are the critical stress and strain. The grouping method is even more exactness，more corresponding to facts，more economic and safe than the tradition method. It would have practical value in the rock base engineering.

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EXPERIMENTAL INVESTIGATION ON FRACTURE OF THREE TYPES OF UNDERGROUND CAVERNS

SONG Yimin1，PAN Yishan2，ZHANG Mengtao2，SHI Huiji1

2010, 29 (S1): -2745 doi:
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[PDF 354 KB] (1064)

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To explore the fracture process and mechanism of underground caverns，three types of fractures which include primary and remote fracture，V-shape notches and zonal disintegration，have been studied by model experiments. The prefabrication cavern models were loaded under biaxial compressive loading and triaxial compressive loading. The fracture extension of the surrounding rock of model caverns are monitored by the white light digital speckle correlation method and acoustic emission. Based on laboratory test results，three types of fracture mechanisms were analyzed. The experimental results of primary and remote fracture show that the remote-fracture mechanical mechanism is the tensile strain concentration，and the tensile strain is the main focus and the combined effect of tension and compression. The experimental results of V-shape notches show the surrounding rock fractures of underground caverns form in the local area of the border of the model caverns，then extend to form the V-shaped fracture zones. The follow-up fracture in the tip of V-shape notches of model caverns expands to the surrounding rock of model caverns. The experimental results of zonal disintegration show the circular fracture of the deep surrounding rock of model caverns forms in the tip of the local fracture area of the border of model caverns，and extend to the deep surrounding rock. At the same time，a non-fracture zone has formed intermediately in the border of underground caverns and the circular fracture of surrounding rock.

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ERROR ANALYSIS OF STORAGE-VARIABLE TRANSIENT PULSE METHOD FOR PERMEABILITY MEASUREMENT

WANG Ying，LI Xiaochun，WEI Ning

2010, 29 (S1): -2754 doi:
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[PDF 426 KB] (769)

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Storage-variable transient pulse method is an advanced permeability measurement method for its properties of fast operation(testing time less than 2.5 h)，large range(testing range from 10－7 D to 10－1 D) and high precision(testing error less than 5%). First of all，the theoretical features，design principles and testing processes of this new method have been introduced. And then，the methodological and technological error sources have been discussed，including the device attached，the surroundings influenced and man-made produced. All the error sources have been classified to 6 kinds of error factors which have a great impact on measurement testing. The impactions have been analyzed categorically and systematically by using ANSYS modelling. The last but not the end，matters needing attention during design，manufacture and operation have been discussed，moreover，useful ways and means which can cancel error factors or reduce error effects have been proposed. As a result，the device will be improved，and the testing will be rather rational，and the precision will be furthermore accurate.

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HETEROGENEOUS FEATURES OF STATE OF TECTONIC STRESS FILED IN NORTH CHINA AND DEEP STRESS IN COAL MINE

CUI Xiaofeng1，XIE Furen1，LI Ruisha2，ZHANG Hongyan1

2010, 29 (S1): -2761 doi:
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[PDF 417 KB] (814)

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The North China area is divided into 11 sub-districts. Based on the recent 1 111 focal mechanism solutions of moderate and small earthquakes in North China，distribution features of the principal stress direction are analyzed employing grid test method. The result shows that the horizontal action plays a main role in the present tectonic stress filed in North China and the predominant directions of the maximam principlal compressive stress are NEE and EW. The directions of the maximam principlal compressive stress are EW in Tangshan sub-district and Southern Shanxi sub-district. The directions of the maximam principal compressive stress in other sub-districts of North China are NEE with values between 60° and 80°. The in-situ stress measurement by hydraulic fracturing in deep rock in Wanfu coal mine shows that the direction of the maximum horizontal compression stress is between 40° and 80°，which is well consistent with the analysis result of focal mechanism solutions of moderate and small earthquakes in the southwest of Shandong Province. Based on a tectonic comparison，the deep stress state in Wanfu coal mine is closely related to the tectonic stress filed in the southwest of Shandong Province.

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COALSEAM THICKNESS PREDICTION WITH GEOSTATISTICS

DU Wenfeng，PENG Suping

2010, 29 (S1): -2767 doi:
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Coalseam thickness is necessary data for coalmine design and mining. The correct predication result of coalseam thickness not only can provide good geology guarantee for coalmine，but also can bring great economic benefits. Coalseam predicting can be calculated using fitting or regression analysis method according to the known borehole coalseam thickness，but because of the limitation of borehole data amount，there are large errors existenting in predicting thickness between the wells or wells outside area. Seismic data have a good continuity in the transverse，if sparse borehole data could be combined with dense seismic data，it is helpful to increasing the thickness predicting precision between the wells or wells extrapolating zone. Cokriging method is a dualistic，unbiased and optimal interpolation method in geostatistics，and based on regional variables theory and variogram basic tool. Borehole coalseam thickness and seismic amplitude in the space distribution have some regulation and local randomicity，so they can be described as regional variables，and can be simulated by variogram，the thickness estimation can reflect thickness variety regulation of well data，also can direct variety trend of seismic data. According to actual measurement thickness data on the roadway coalseam exposing points in the research area，some Cokriging predicting thickness examination have been done，and the predicting thickness error has become lower. The predicting precision has largely increased. The thickness predicting method is especially suitable for some coal mines which have done 3D seismic exploration.

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STUDY OF DISTRIBUTION CHARACTERISTICS OF IN-SITU STRESSES FOR HUOZHOU MINING AREA

WANG Lianguo1，LU Yinlong1，YANG Xinhua2，GAO Feng1，ZHANG Hualei1，
LI Hailiang1，YANG Feng1

2010, 29 (S1): -2774 doi:
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In-situ stress is formed in rock mass with complex origin and experienced a prolonged geological period，and there are many influencing factors. And in-situ stress is one of the important influencing factors to the deep laneway rock stability in coal mines. The field measurement is systematically carried out by boring stress-relief method with hollow inclusion triaxial strain gauge in primary mineable coal bed of Huozhou mining area and actual survey ground stress data at different positions and depths are achieved. Distribution law of in-situ stress field is obtained by systematically analyzing testing data. It shows that crust of earth in Huozhou mining area is effected by horizontal tectonic stress field. By using FLAC3D program，the model is established to analyze the laneway stability of different orientations based on in-situ stresses and detailed engineering geological condition. Using obtained research results and the maximum horizontal stress theory to study working area of Tuanbai coal mine No.8，the coal roadway roof stability performance is mostly effected by the maximum horizontal stress. The result is helpful to determine mining stope tendency and to choose the calculation parameters of coal roadway supporting design strength. The conclusion has important significance for the safety and high effective product in coal mines.

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EXPERIMENT AND MODEL RESEARCH ON SHEAR RHEOLOGICAL PROPERTIES OF SATURATED SANDSTONE

XU Hui1，HU Bin1，TANG Huiming1，CHEN Jingli2

2010, 29 (S1): -2781 doi:
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[PDF 407 KB] (811)

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Shear rheological experiments on the saturated sandstone of Wuhan Yangtze River tunnel with JQ200 shear rheometer are conducted. Long-term rheological curves in different stress states of saturated sandstone are obtained. Analyzing its rheological properties and comparing with those of dry sandstone，the results show that saturated sandstone¢s rheological properties are much more distinct than that of dry sandstone and its stress threshold is lower. Based on the shear rheological curves，the five-component viscoelastic rheological model is adopted after distinguishing from many rheological models. Then the model is used to simulate the experimental results. In order to simulate the whole shear rheological curves，the I-NVPB model is proposed. Based on the two shear rheological models mentioned above，all the shear rheological parameters are obtained. The comparison between the shear rheological model and experimental results shows that the I-NVPB model is reasonable and it has important engineering significance and popularization value.

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STUDY OF THE APPLICATION OF ENERGY RELEASING AND PRESSURE REDUCING AIM TO EVADE RISK IN WATER-ENRICHED HIGH HYDRAULIC PRESSURE LATENT KARST TUNNEL

ZHANG Xudong1，WANG Haibin2，FENG Mingjun3，DENG Zhe3，4，LI Xiaochun2

2010, 29 (S1): -2791 doi:
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Maluqing tunnel of Yichang—Wanzhou railway goes through a water-enriched high hydraulic pressure latent karst cavity in DK255+978 m，where the water pressure reaches up highly to 160 m and maximum volume of water to 1×106 m3，soil-break and water-inflow disaster had taken place for 19 times. Based on characteristic of large scale of cavity water，high hydraulic pressure，high bedload content，strong destroied power，no foreboding，paroxysmal and intermittence，antinomy between paroxysm and arrearage，etc.，adaptability of treatment measure is defined based on mechanics，such as，seepage enlarged into conflux because of pressure dispersion between inside and outside of the cavity，so that cavity deprives groundwater from aquifer aqueduct and fracture，then，the water together with mud release suddenly. It is found that the principle of energy releasing and pressure reducing (ERPR) should be adopted to evade risk during construction temporary stage and permanent working stage，while the energy stored in the cavity must be released，and water and soil pressure on tunnel and its structure must be reduced，so that plastic district acting on cavity wall due to high pressure doesn¢t develop and connect with the plastic district act on rockmass due to tunnel excavation or water and mud drainage. Boundary of karst cavity，filling component and distribution characteristic must be explored distinctly by synthetical geological forecasting. Pressure and quantity，especially，critical distance determine thickness of pressure bearing rock wall. The feasibility of space-cross-step scheme of drainage aloft and purge filling infra is analyzed and validated.

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APPLICATION AND DOUBLE-DIRECTION CONTROL BOLT SUPPORT TECHNOLOGY OF LARGE SPAN Y-TYPE INTERSECTION IN DEEP COAL MINE

GUO Zhibiao1，2，WANG Jiong1，2，CAI Feng1，2，WANG Fuqiang1，2

2010, 29 (S1): -2798 doi:
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Under geological conditions at deep coal mine，the crossing roadway especially Y-type experienced large deformation. The junction pillar could be the weakest link. Based on in-situ investigation and theoretical study，typical forms of the destruction were summarized. High stress and unrestrained deformation at two sides of junction pillar were two main factors affecting the stability of the cross-section. Deep Y-type large cross-section junction double-control anchor support technology was proposed. The technology has been used in deep intersection engineering in Jiahe coal mine.

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INVERSE ANALYSIS FROM ACTUAL DATA TO DETERMINE GEOSTRESS AND WELLBORE STABILITY

ZHAO Haifeng，CHEN Mian

2010, 29 (S1): -2804 doi:
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[PDF 348 KB] (855)

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A new method based on actual data to determine geostress is introduced. Without the traditional assumption that wellbore is cylindrical，the relationship among wellbore deformation，rock mechanical properties，geostress，pore pressure and mud density is established by using dual media elastic mechanics. Using this relationship，geostress and pore pressure are inverted from mud log and conventional log. Then collapse pressure and fracture pressure are calculated. The results show that the calculated fracture pressure is in good agreement with the actually measured value，and the inverted pore pressure is in agreement with the practical mud density. The agreement verifies the rationality of this new method. It is a breakthrough to determine earth pressure and pore pressure from actual mud log and conventional log. Due to the basis of rigorous mechanical model and actual data，this new method has high degree of accuracy. With measurements while drilling，this method can predict pore pressure，geostress and wellbore stability at real time. So the method may be wildly used.

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MEASURED DEFORMATION AND DEGREE OF DISTURBANCE ANALYSIS OF EMBANKMENT DURING PIPE JACKING THROUGH EXPRESSWAY FOUNDATION

WANG Bin1，CHEN Shuai1，TAO Baifeng2，TAN Hao1

2010, 29 (S1): -2812 doi:
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When the pipe jacking has been put through sand foundation consolidated under expressway embankment loading，differential settlements will be produced in cross section and longitudinal direction of the embankment due to the ground disturbance and ground loss caused by pipe jacking construction. Field observation and analysis indicate that the index，whether the increment of the slope caused by differential settlement in cross or longitudinal direction less than 0.5% or not，can be used to control and predict the stability of the embankment dynamically during pipe jacking or water depression. It can prevent the road surface from cracking efficiently. Field experiment and measured law show that the settlement of the disturbance zone is advanced and instantaneous during pipe jacking construction，to sand ground layer，the area of the disturbance zone is larger than the value calculated according to soft soil theory. The disturbance zone is mainly in the range of 1 m beyond the pipe wall exine and expand based on this. The percentage to the compressibility increment of the soil above the pipe axis could be more than 50%，and the void ration can be larger than 35%，the strength is decreased plasticity index has been reduced in different degrees，all these lead to the reconsolidation of the soil in the disturbance zone，which brings forward the settlement of the embankment directly. Compression is the main characteristic of the soil under the pipe axis. When the pipe jacking is through sand soil layer，more attention should be paid to water depression during pipe jacking and open caisson construction which can bring disadvantage to expressway embankment.

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STUDY OF SIMULATION MATERIALS OF AQUIFUGE FOR SOLID-LIQUID COUPLING

HUANG Qingxiang1，ZHANG Wenzhong1，HOU Zhicheng2

2010, 29 (S1): -2818 doi:
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[PDF 332 KB] (977)

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The stability of clay aquifuge is the key factor of water conservation mining and water and soil erosion in coal mining. The exploration of new simulation materials and its proportions for clay aquifuge are the basis of the aquifuge stability simulation. Based on the orthogonal tests for the simulation of physico-mechanical and liquid characteristics of clay aquifuge，it is found that the silicone oil is the best additive material for low strength and non-hydrophilic simulation，and the vaseline is the best additive material for plastic deformation simulation，and the clay has important effect on the strength，plasticity，and fissure close feature of simulation materials. Furthermore，a series of tests are carried out for the simulation of the strength，plasticity and the liquid quality of the aquiclude，and the simulation materials and its proportions which can simulate complete stress-strain curve and the water reactivity of aquifuge are obtained. Thus，the technical problems of the plasticity and water reactivity simulation are solved. At last，the solid-liquid coupling simulation experiment of long wall mining face for Yushuwan coal mine is carried out，and the simulation materials and its proportions are proved reliably for clay aquifuge simulation. It is also found from the simulation that the mining induced upward cracks and downward cracks are the key factors of aquifuge stability.

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ANALYSIS OF MECHANISM OF MID-PARTITION ECCENTRIC COMPRESSION AND CONSTRUCTION EFFECT ON SUPER-LARGE SECTION MULTI-ARCH TUNNEL

XU Chongbang1，2，XIA Caichu1，3，WANG Hualao2

2010, 29 (S1): -2826 doi:
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[PDF 446 KB] (690)

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The mid-partition of a multiple-arch tunnel is very important and attracts much attention in tunnel designing and constructing as it is a main support structure of tunnel，and affects the integrated stability of tunnel engineering. The mid-partition destabilization is eccentric compression instability in which the mechanics reason is unevenly stressing，so，controlling eccentric compression of the mid-partition control is critical to the control stability of mid-partition. The geological eccentric compression of tunnel engineering and the construction eccentric compression which come from asymmetric construction are the basic cause，and according to stress state of mid-partition，the condition and the position of eccentric compression from the geological eccentric compression and the construction eccentric compression are determined. The effects of construction procedure under the geological eccentric compression and the construction eccentric compression are analyzed through the computation simulation for different construction procedures of multi-arch tunnel by the finite element method. Optimum analysis for construction scheme according to the obtained law is completed. At last，the example of the multiple-arch tunnel with eight traffic lanes is given.

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INFLUENCE OF MICROENVIRONMENT ON RHYOLITE
WEATHERING RATE

ZHANG Zhongjian1，2，YANG Zhifa1，ZHANG Luqing1，TAO Kejie3，PHAM TRUNG-HIEU2，3

2010, 29 (S1): -2832 doi:
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[PDF 391 KB] (834)

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Through studying of weathering of two rhyolite light stands built in 1520 AD in Confucius Temple of Quzhou，Zhejiang province，their weathering rates in moist environment are elicited (0.4–9.7 mm/(100 a))，and the differences between light stands，different parts of one light stand，and the same part in different aspects are also discovered. For examples，(1) The weathering rates of the top disks in north aspect of No.1 and No.2 light stands are 4.3 and 9.7 mm/(100 a)，which are larger than these in south aspect(datum mark and 2.1 mm/(100 a)). But that are quite different in the bottom，the weathering rates in southwest aspect of light stand No.1 and in south aspect of No.2 are the largest in the bottom，which are 3.1 and 2.1 mm/(100 a)，respectively. Such differences are caused by the microenvironment like wind，rainfall，solar radiation and so on. (2) Compared with other part of the light stands，the weathering rates of candle holes in top disks are the smallest，which are no more than 1.0 mm/(100 a)，because they are isolated from air for always filled with water (mostly are rainfall). From the above，a basic idea is proposed to obstruct factors that influenced weathering for long-term protection of the light stands.

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2010, 29 (S1): -2839 doi:
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[PDF 276 KB] (1831)

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STUDY OF DEFORMATION BEHAVIOURS OF LIMESTONE UNDER CYCLE TRIAXIAL COMPRESSION WITH DIFFERENT CONFINING PRESSURES

HAN Lin，LIU Xiangjun，MENG Yingfeng，LI Gao，LIU Hong，WU Xiaolin

2010, 29 (S1): -2844 doi:
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[PDF 276 KB] (887)

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The mechanical behavior of rock under cycle load is the one of most important factors which could effect on the long-term stability of rock matrix. So the rock behavior and evolving regular of rock under circulation load are needed to be researched. The samples are selected through the wave velocities of compression wave and shear wave. The rock deformation tests are measured under different confining pressures，constant cycle upper limit confining pressures and triaxial altering confining pressure cycle loading. Triaxial altering confinement pressure cycle test is performed on the GCTS–1 000 rock mechanic test system. The test results are as follows：(1) The deformation of limestone forms a closed plastic sluggish winding when the limestone is loaded or unloaded under altering or constant confining pressure. The areas of plastic sluggish winding diminish succession on the axial deformation；the areas of plastic sluggish winding under altering confining pressure increase succession on the radial deformation；the areas of plastic sluggish winding under constant confining pressure are almost equal. (2) In the triaxial altering confining pressure test，the residual deformation displays a scaling down tendency in condition that the confinement pressure increases and the cycle upper limit stress does not change. The developing trend of axial deformation and radial deformation is contrast to the result of residual deformation. (3) The deformation moduli of cycle loading or unloading progress are different and the deformation moduli of unloading progress are bigger than the value of loading progress. (4) The deformation moduli measured under altering confinement pressure are bigger than the deformation moduli measured under constant confinement pressure. Through experiments，the deformation character and rock elastic parameters of limestone under triaxial altering confinement pressure cycle exist divergence.

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NUMERICAL ANALYSIS OF EFFECT OF NORMAL FAULT ACTIVITY ON ROAD MOUNTAIN TUNNEL PROJECT

XIONG Wei1，FAN Wen1，2，3，PENG Jianbing1，2，DENG Longsheng1，YAN Furong1

2010, 29 (S1): -2852 doi:
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[PDF 395 KB] (914)

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According to the structural characteristics and active forms of normal faults in Weihe River Basin，the finite element method is used to simulate the force and deformation of tunnel lining when the road mountain tunnel passes through the normal fault. Calculation is mainly focused at the four major factors which are the movement quantity of fault，the inclination angle of fault，the depth of tunnel and the across angle between tunnel and fault. And the failure modes of lining are concluded. The result shows that the sensitivity of impact of four factors on the lining force and deformation reduced in turn. On the 40 m scope of both sides of the fault fissure is the central location of force and deformation. When the inclination angle of fault is less than 50°，the force of lining is similar to that of cantilever beam with one end fined. Through analyzing and calculating the relative settlement quantity，longitudinal stress and shear stress of the lining，the main failure mode of lining will be divided into three categories. First type is extension-compression，which is actived by large longitudinal stress，then it is extension breakage mainly with compression breakage. Second type is direct-shear，which is controlled by large sheer stress. And the third type is combination of the extension-compression breakage type with direct-shear breakage type.

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STUDY OF ROCK MECHANICAL PROPERTIES AND RAPID EXCAVATION METHOD FOR HARD ROCK ROADWAYS IN DEEP COAL MINE

YUAN Wenhua1，MA Qinyong1，2

2010, 29 (S1): -2857 doi:
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[PDF 207 KB] (1019)

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Experiments are carried out to study the hard sandstone under uniaxial compression and different confining pressures with triaxial compression by the rock mechanics testing machine RMT–150B in deep coal mine，and basic mechanical properties of sandstone are measured. According to the rock stress-strain curves，strength properties and deformation characteristics of deep-seated rock are analyzed. The results show that rock compression strength increases by 40.3% with confining pressure from 10 to 15 MPa. The deformation and failure pattern of sandstone are closely related to confining pressure. The slope of main stress difference-strain curves are steep significantly with the increasing of the confining pressure. Based on the mechanical properties of rock，the 42 mm in diameter drill bit is adopted for the cutting holes and the 32 mm in diameter drill bit is used for the surrounding holes in order to save the drilling time. The different steps of millisecond inclined cutting with medium-length hole are proposed，and the depths of 2.2–2.5 m for blasting hole are reasonable which are beneficial to the footage. The surrounding hole with small diameter is beneficial to the roadway forming.

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CONSTRUCTION TECHNOLOGY AND MONITORING ANALYSIS OF SUBWAY TUNNEL INGATE UNDER COMPLEX CONDITION

JIANG Qingqing1，HUANG Xiaoyang1，ZHOU Kai2，CHEN Zhanfeng1

2010, 29 (S1): -2865 doi:
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[PDF 435 KB] (922)

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Subway tunnel ingate is the weak links of the tunnel structure. The construction under complex conditions easily leads to the collapse of vault and the settlement of ground and surrounding structures. Taking the Yijing road station to Huangbeiling station tunnel ingate project of Shenzhen Metro Line 5 for example，the construction techniques and monitoring methods are described. Construction experience and monitoring analysis show that：(1) because of using double-pipe grouting，hollow anchor grouting，big pipe shed and ductile grouting support methods，and constructing in accordance with monitoring results，the settlements of the ground and surrounding structures are controlled effectively；(2) double-pipe grouting reinforces the underground structures and the surrounding soil obviously；(3) big pipe shed construction is simple and rapid，and it can prevent the large area collapse of the vault，but the construction may lead to the water loss and ground settlement；(4) and the enclosure of lining structure is an effective method to control the horizontal convergence of the ingate section.

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STUDY OF GA-SARMA ALGORITHM OF CRITICAL SLIP SURFACE OF ROCK SLOPE

TAN Rujiao1，LI Mingsheng1，ZHANG Jiangeng1，HU Ruilin2

2010, 29 (S1): -2871 doi:
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[PDF 266 KB] (997)

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In view of limitations in searching the critical slip surface of rock slope of the existing domestic and international software for limit equilibrium slope stability analyses，a new method named GA-Sarma algorithm for rock slope stability analyses is proposed. Just as its name implies，GA-Sarma algorithm is implemented based on Genetic algorithm and Sarma method. GA-Sarma algorithm assumes the morphology of slip surface to be a broken line with traceability to extend along the discontinuous surface structures，and the slice boundaries are consistent with rock mass discontinuities such as rock layers，faults，cracks，and so on. GA-Sarma algorithm is a revolutionary method that is suitable for global optimization of the critical slip surface for rock slopes.

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EXPERIMENTAL STUDY OF MICROSTRUCTURE AND
MECHANICAL PROPERTIES OF ROCKS FROM DONGHEKOU LANDSLIDE

SUN Ping1，2，YIN Yueping 3，WU Shuren1，2，CHEN Liwei4

2010, 29 (S1): -2878 doi:
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[PDF 536 KB] (877)

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Donghekou landslide is a typical rapid and long run-out landslide located in Qingchuan County triggered by the 2008 great Wenchuan earthquake. It starts from the elevation of 1 300 m and causes 780 deaths，with a total long run-out of 2 400 m. This landslide is composed of limestone and dolomite limestone of Sinian system，carbon slate and phyllite of Cambrian system. Field investigations indicate that as for the Donghekou landslide，the microstructure and macroscopically mechanical property of the rock on sliding mass play an important role in the starting-up of the landslide under the action of earthquake. Therefore，by using the ORTHOPLAM microscope，the RMT–150C rock mechanics testing system and the 600 kN hydraulic universal testing machine，a series of tests have been carried out to study the microstructures and mechanical properties，such as the tensile strength，the compression strength and the shear strength of rocks from Donghekou landslide. The microstructure test results show that the mineral component of rock samples is very complex，and most of the rocks have experienced more than two deformation and metamorphic processes. And the mechanical test results indicate that water is an important factor for the mechanical properties of rocks，and the tensile strength，the compression strength and the shear strength are different at the dried state and saturated state. At the same time，the structural plane also plays a significant role in the mechanical properties of rocks.

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ROCK SLOPE STABILITY ANALYSIS BASED ON HOEK-BROWN FAILURE CRITERION

LIU Lipeng1，YAO Leihua1，CHEN Jie1，WANG Chenghu2

2010, 29 (S1): -2886 doi:
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[PDF 314 KB] (1258)

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The choice of the strength criterion and the mechanical factors is obviously important to the stability analysis of the slope，whether by traditional limit-equilibrium analysis or numerical simulation analysis. Based on the nonlinear strength criterion，Hoek-Brown strength criterion，the geology strength index GSI，the empirical constants of rock mi，the factor which depends upon the degree of disturbance to the rock mass，have been subjected to blast damage and stress relaxation D，and the height of slope H and the angel of slope are chosen as the main factors that control the stability of slope. The study of those factors has been carried out using a 2D slope stability program Slide. Conclusions can be drawn as follows：(1) with the increase of GSI value，the stability factor F shows increase trend in the form of exponent；(2) with the increase of mi value，F shows obviously different trends，increase or decline，in the different ranges of the GSI values；(3) with the increase of D value，F shows decline trend in the form of line；(4) with the increase of the height of slope H，F shows the decline trend in form of negative exponent；and with the increase of the slope angle ，F shows decrease in the form of polyline with different slopes，in the different ranges of . According to the limit value of the rock uniaxial compressive strength in the rock masses classification criterion which has put forward by E. Hoek et al，the stability of rock slopes is analyzed and the stability factor charts are drafted. Finally，the stability chart is used in a rock slope engineering，and the result shows that it can be used to estimate the range of the rock slope stability factor effectively and consistent to the quantitative analysis.

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SLOPE STRUCTURE AND EXCAVATION DEFORMATION REGULARITY OF HIGH SLOPE COMPOSED WITH RED BED ACCUMULATION BODY

WANG Huanlong1，SUN Yi2，ZHOU Depei1，XIAO Shiguo1

2010, 29 (S1): -2894 doi:
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[PDF 399 KB] (855)

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The high red bed accumulation body slope is a particular type in red beds areas. It is widely distributed in Guangyuan—Bazhong expressway. Starting from the reform process of red bed accumulation body，and based on the geological checking investigation，the red bed accumulation body is divided into M type，double-M type and single side type by slope top shape；and at the same time，the red bed accumulation body is divided into layered accumulation body，mass rock and soil accumulation body，clay layer beneath mass rock and soil accumulation body，mass rock and clay mix up big solitary stone by soil types and accumulation types. The excavation deformation characteristics of the four types are analyzed through the field survey data and assisted by MIDAS/GTS (MIDAS/geotechnical and tunnel analysis system). The superficial partial slumps appear in all the types of accumulation body slopes. In layered accumulation body，tractive consequent landslide is the main pattern of sliding. While circular sliding face and plane sliding along the bedrock appear in the accumulation body which includes mass rock and soil or clay. The slope deformation and failure types with solitary stone changed obviously by variety of size and location of inside solitary stone. The geological checking investigation and numerical simulation results also show that besides structure type of accumulation body，the shape of bedrock and obliquity can also affect the deform characteristics. The characteristic of red bed accumulation body has the same diversification with the red bed slope. The results provide a basis for analyze the disease patterns and mechanism，and also provide a foundation for the design of red bed accumulation body area.

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STUDY OF TREES RESISTANCE EFFECT TEST ON ROLLING ROCK BLOCKS

HUANG Runqiu1，LIU Weihua1，GONG Manfu2，ZHOU Jiangping3

2010, 29 (S1): -2901 doi:
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[PDF 297 KB] (795)

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The visible resistance of trees to rolling rock is the efficient measurement to prevent potential unstable rock mass. Based on the theory analysis of collision probability between rolling rock and trees，resistance effect experiment of trees on rolling rock is designed. Through the experiment，the collision probability between rolling rock and trees，rolling rock displacement after collision，and the change of velocity and kinetic energy due to the collision are studied. And the calculation and analysis method are attained for the collision probability between rolling rock and single row or several rows of trees，for the probability of at least k times collision between rolling rock and trees，and for the number of tree row needed to collide k times，and the correctness is verified through another experiment. Based on the analysis of the change of rolling rock movement displacement after collision to trees，it shows gets that rolling rock movement displacement on platform could decrease by 80%–100% after collision to trees，which accountes for 44.86% of collision in total to trees. The proportion more than 20% is up to 85.11%. After anyone collision，the velocity of rolling rock could decrease to 55% of that before the collision，and corresponding kinetic energy could decrease to 30%. So the number of tree row needed could be calculated when trees are used as the passive prevention measurement to dangerous rock mass. These conclusions provide proof to determine the number of tree row that is needed to prevent rolling rock，and they have practice significant to the prevention of slope geohazards.

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SENSITIVITY ANALYSIS OF MODEL PARAMETERS AND υ-SVR
MODEL OF SLOPE DEFORMATION DUE TO EXCAVATING FROM
OPEN-PIT TO UNDERGROUND MINING

WANG Yunfei1，2，ZHENG Xiaojuan3

2010, 29 (S1): -2907 doi:
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[PDF 234 KB] (760)

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Based on the improved support vector regression(u-SVR) principle，the open-pit mine slope deformation u-SVR model is established which represents the nonlinear variation rule due to the disturbance of excavation from open pit into underground mine. u-SVR model is applied to Xingshan iron mine excavating from open pit to underground mining. The results show that the forecast value which is close to true value and calculation is convenient，and the validity of the improved support vector regression principle is verified by studying the open-pit slope nonlinear deformation rule with virtue of the secondary mining perturbations. The sensitivity of the parameters is analyzed，intuitively reflecting the effect of C，u on mean absolute error(MAE) and the number of support vectors，and the reasonable ranges of the parameters C，u are determined，that is，[1 000，5 000] for parameter C. The interval is larger，but the effect of parameter C on the generalization performance should be considered when selecting parameter C；for parameter u = [0.028，0.125] is a rather reasonable range.

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STUDY OF GEOLOGICAL ORIGIN MECHANISM OF TANGJIASHAN LANDSLIDE AND ENTIRE STABILITY OF LANDSLIDE DAM

LI Shouding1，LI Xiao1，ZHANG Jun2，HE Jianming1，LI Shihai3，WANG Yangchun4

2010, 29 (S1): -2915 doi:
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[PDF 596 KB] (1846)

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By geological survey and engineering geological characters analysis of Tangjiashan landslide，the landslide types and geological origin mechanism are studied. On the base of the rock mass structure analysis and surface displacement monitoring，the entire stability of landslide dam is studied. The conclusions are achieved：(1) Tangjiashan landslide is of high speed rock slide triggered by earthquake，and is located in a consequent slope of complex overturned fold. Landslide sliding zone is possibly situated in interbedded shear zone. (2) Landslide dam material is mainly block rock mass overlying with weathered incompact accumulation，and entire stability is good. Flood affected the surface displacement of landslide dam with the maximum displacement of 140 mm. Increment of surface displacement is down after flood，and landslide dam is stable now. (3) The chained hazard study of earthquake landslide→dammed lake→breach→flood with domino effect should be emphasized. Engineering geological survey and seismic risk study of slope are included interbedded shear zone.

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ADVANTAGES STUDY OF VACUUM PRELOADING AT BOTTOM OF SOIL LAYER FOR RECLAMATION PROJECTS

VU Manh Quynh1，2，WANG Baotian1

2010, 29 (S1): -2926 doi:
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[PDF 279 KB] (2606)

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An experimental program is conducted to study the advantages of vacuum preloading applied at the bottom of soil layer，named VAB method，in comparison with vacuum preloading conventionally applied to the top of soil layer，named VOT method，for reclamation projects like new slurry ponds. The modified apparatus has capacity of applying designated vacuum pressure of 80 kPa to soil body；otherwise it is also possible to measure the pore pressure at different depths of the soil column，the settlement and the volume change along elapsed time. Two series of test are implemented on silty clay dredged from Qinhuai River in Nanjing，China. The study concludes that the vacuum preloading has generally remarkable effects on soil improvement. However，the effects by using the VAB method are much better than that by using VOT method. It is found that the water content more decreased by about 10%；the dry density more increased by about 11%. The undrained shear strength has increased by about 35%. The final settlement is about 22% greater. The results also demonstrate that the VAB method is less time consuming and the improvement is steadier along the soil depths. In addition，the maintenance of vacuity is much more convenient. The essential difference between the two methods is that for the VOT method，the relative water table level remains unchanged in soil mass during vacuum procedure. The soil is therefore always in submerged and saturated states. On the contrary，with the VAB method the water table level inside the PVDs falls down very quickly to bottom of soil layer after the vacuum pressure is fully applied. The water table level in soil mass also drops with elapsed time. The soil is not in submerged state anymore and may change from saturated to unsaturated state.

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ANALYSIS OF SLOPE STABILITY UNDER SEEPAGE BY USING
ABAQUS PROGRAM

ZHANG Xiaoyong，DAI Zihang

2010, 29 (S1): -2934 doi:
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[PDF 325 KB] (3678)

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In order to analyze the slope stability under seepage，the coupling effect of seepage field and stress field needs to be considered. The ABAQUS finite element program has good coupling analysis function of deformation and seepage，and the seepage field can be coupled with the stress field directly. So the ABAQUS finite element program which is combined with strength reduction technique was used to analyze the slope stability under seepage，and the safety factors of slope stability were obtained. The shapes and positions of seepage of saturated surfaces and the most dangerous slip surfaces could be revealed by using the strong post processing functions of ABAQUS program. To verify the accuracy of this method，it was compared with the Sweden slice method and simplified Bishop method that both were based on the traditional limit equilibrium theory. The engineering example showed that the strength reduction FEM based on the software ABAQUS could overcome the disadvantages of the traditional limit equilibrium methods，and its results were more reasonable and reliable. This method was effective to analyze the complicated problem of slope stability under seepage，and the conclusions could provide references to the engineering practice. Meanwhile，the influences of the permeability of soil on the positions of seepage of saturated surfaces and slope stability were made a mass of analysis and comparison，and the calculation indicated that choosing finite element model borders influenced the positions of seepage of saturated surfaces and slope stability. So finite element modeling should choose calculation borders reasonably.

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INDOOR SCOUR MODEL TEST OF EXPRESSWAY SLOPE ECOLOGY PROTECTION USING COCONUT FIBRE NETS

CHENG Ye1，2，FANG Liang3，ZHAO Junfeng3，ZHOU Cuiying1，2

2010, 29 (S1): -2942 doi:
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[PDF 344 KB] (881)

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According to the situation of Shaoguan-Ganzhou expressway slope project，the indoor scour test model of expressway slope ecology protection was designed and made. 378 groups scour testing were carried out which included three kinds of plants(i.e. Tall fescue，Dogtoothgrass，Trilobate wedelia)，three kinds of slope angles(i.e. 1∶0.75，1∶1 and 1∶1.15)，seven kinds of protection forms(i.e. coconut fibre nets，three-dimensional nets，three-dimensional nets plus coconut fibre nets，wire netting，wire netting plus coconut fibre nets，geocell，geocell plus coconut fibre nets)，three kinds of rainfall intensities(i.e.，40，80，120 L/(104 s·m2)) and two plant growth periods(i.e. 2-month and 5-month). The testing results show that the protection effect which used coconut fibre nets is markedly better than that of three-dimensional nets，wire netting，and geocell. The slope ecology protection which used coconut fibre nets solely or coconut fibre nets and other protection forms together can availably reduce the rainstorm scour especially when the tall fescue and Dogtoothgrass growth 2-month and the slope angle is bigger than 1∶1，or Trilobate wedelia growth 2-month or 5-month.

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ANALYSIS BETWEEN NUMERICAL AND FIELD TESTS OF HIGH FILL REINFORCED WIDENING EMBANKMENT

WANG Jiaquan1，ZHOU Jian2，3，CONG Lin4，DENG Yibing5

2010, 29 (S1): -2950 doi:
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[PDF 331 KB] (928)

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Associating with mountain freeway widening project，the field test of high fill old and new embankments of geocell treatment was carried out to analyze the lateral displacement，settlement and soil pressure laws of high fill embankment，and the effect of geocell treatment is also studied. Based on field test，the three-dimensional thin membrane element is used to simulate geocell，and three-dimensional elastoplastic model is proposed. The geocell reinforced characteristics and the deformation law of high fill widening embankment by the sensitivity analysis of the relevant parameters are analyzed. The results show that the three-dimensional thin membrane element can better reflect treatment effect that geocell reinforces high fill embankment. Compared with the field test，the field reinforced effect by using numerical experiments is achieved，and the law of geocell treatment of high fill embankment through the analysis of parameter change of geocell，filling and the spacing of reinforcement materials is also achieved，and thus geocell reinforced mechanism is further discussed. Under itself gravity loads of widening embankment，the vertical displacement mainly is concentrated in the upper part of the widening embankment and lateral displacement gradually is reduced from the top surface to the bottom of embankment. Geocell layer plays the role in decentralizing the load transfer，reducing the lateral deformation and differential settlements. The higher moduli of filling and reinforcement material are，and the smaller reinforcement spacing is，and the reinforcement effect is better. The reasonable distance for the geocell spacing is 2–3 m. These conclusions may be useful to the design and analysis of reinforced-embankment on high fill and the interface between new and old embankments in widened embankment.

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QUANTITATIVE ANALYSIS OF ORIENTATION DISTRIBUTION OF SOIL GRAINS BASED ON SLOPE-ASPECT THEORY

WANG Baojun，ZHANG Mingrui，SHI Bin

2010, 29 (S1): -2957 doi:
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[PDF 560 KB] (958)

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A new technique for quantitative analysis of the orientation distribution of soil grains from SEM images，slope-aspect technique，was described in this paper. The pixels at the edge of the particles of SEM were abstracted by the method of slope analysis. Because the aspect values of the pixels at the edge of the particles are orthogonal to the orientation of the particles，the orientation characteristics of a SEM image of soil samples can be obtained by quantitatively analyzing the aspect of the pixels at the edge of the particles in SEM. Some quantitative analysis techniques，including rosette diagrams，index of anisotropy and main orientation angle were also used. Through some examples，the slope-aspect technique is proved to be an efficient technique in examining orientation patterns of clay or sand soil microstructure，and it can provide more reasonable rosette histogram，index of anisotropy and main orientation angle. It also shows that the results in low slop classes can not present the orientation characteristics of whole sample because of noise and algorithmic error. But aspect values of pixels with higher slope class on the boundaries of particles can well present the orientation pattern of soil samples.

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RELIABILITY ANALYSIS OF STABILITY OF A MUNICIPAL SOLID WASTE LANDFILL

ZHANG Wenjie1，QIU Qingwen1，QIU Zhanhong2

2010, 29 (S1): -2963 doi:
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[PDF 209 KB] (833)

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Waste is heterogeneous and its physico-mechanical parameters are characterized by extreme variability. Unit weight and shear strength of waste were measured by laboratory test on boring samples and the corresponding variation trend and probability characteristics were analyzed. Random parameters were generated according to the stratified and the overall probability characteristics. Reliability analyses were carried out using Monte Carlo method. The results show that as buried depth increases，effective cohesion of waste decreases whereas effective internal friction angle increases. There is a negative correlation between them. However，they are independent of each other in each waste layer. Standard deviation of safety factor obtained from reliability analyses considering stratified probability characteristics is smaller than that corresponding to overall probability characteristics. This illustrates that the variation trend and probability characteristics of waste parameters must be examined before a reliability analysis.

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MODEL TEST AND NUMERICAL SIMULATION STUDY OF DYNAMIC
CHARACTERISTICS OF ROCK SLOPE UNDER
BLAST LOADING

ZHONG Dongwang，WU Liang，CHEN Hao

2010, 29 (S1): -2971 doi:
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[PDF 551 KB] (1006)

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The indoor experimental method of concrete slope model and finite element model are considered to study dynamic characteristics of rock slope under blast loading. The result shows that the propagation law and attenuation characteristics of the detonating earthquake wave on slope are different to the condition of level ground，and the attenuation of peak particle vibration is small with distance. The vertical and horizontal attenuation indices of peak particle vibration are 0.76 and 0.42，respectively. Comparing the peak particle vibration of the top and other particles of the slope，peak particle vibrations of the top particles are larger than those of other particles，so there are vibration enlarging effect at the top particles of the slope. Comparing the peak particle vibration of point No.3 facing blasting source and point No.4 backing blasting source，the peak of vertical velocity is reduced by 72.7% and the peak of horizontal velocity by 67.6%，so the measures of damping ditch can reduce the value of peak particle vibration greatly and can improve the stress state of the slope under blasting load. With the experimental results，the particle velocity and the index of regression equation are in the same magnitude with the test data，and the peak particle velocity increases with its height，too. The calculation results can give the reality particle vibration law of the slope under blast loading well.

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GIS BASED CERTAINTY FACTOR ANALYSIS OF LANDSLIDE TRIGGERING FACTORS IN WENCHUAN EARTHQUAKE

XU Chong1，DAI Fuchu1，YAO Xin2，3，CHEN Jian4，TU Xinbin1，CAO Yanbo1，XIAO Jianzhang1

2010, 29 (S1): -2981 doi:
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[PDF 1289 KB] (1897)

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On May 12，2008 at 14：28(local time)，a catastrophic earthquake with surface wave magnitude of 8.0 struck the Sichuan Province of China. Tens of thousands of landslides were triggered by this earthquake over a broad area. 48 007 landslides were interpreted from aerial photographs and multi-source remote sensing imageries，and they are verified by field investigation. Based on the interpretation results，landslide triggering factors with certainty analysis is carried out by means of GIS spatial analysis. The 12 impact factors contributing to the Wenchuan earthquake-induced landslide occurrences include stratigraphic，lithology，main faults，seismic intensity，macroscopic epicenter，surface rupture points，slope gradient，aspect，profile curvature，elevation，drainages，and roads. The certainty factor analysis result shows that five categories of high landslide susceptibility value are as follows：(1) stratigraphic of Cambrian，Ordovician，Permian and Carboniferous，lithology of intrusive rock group and limestone rock group；(2) Wenchuan earthquake-induced landslides are most affected by the main central fault，and also controlled by the Qianshan fault，the little impact for Houshan fault；(3) there are correlations between landslide susceptibility and seismic intensity，distance from the epicenter and surface rupture zone；(4) slope gradient of more than 40°，aspects of east and southeast directions，elevations between 1 000 m and 2 000 m，especial between 1 000 m and 1 500 m were susceptible for landslide occurrence；and (5) distance to drainages is less than 400 m and less than 2 000 m away from roads. The results show that the numerical intervals of each factor are inclined to landslides. This work is the basement for further study of earthquake- induced landslides hazard evaluation and prediction.

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ROAD HIGH CUTTING SLOPE STABILITY ANALYSIS UNDER INFLUENCE OF BLASTING FOR EXCAVATION

GAO Wenxue1，LIU Hongyu1，2，LIU Hongyang1，XU Shuhuan1

2010, 29 (S1): -2987 doi:
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[PDF 400 KB] (933)

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High rock slope is a common type of slope in mountainous areas during highway construction，and the issue of its stability has been closely followed by geotechnical research scholars. Based on research of the blasting vibration and its effect during the excavation of cutting slope，the analytical methods and the evaluation criteria of the high rock slope¢s dynamic stability were discussed. Taking Yanqing—Longqingxia road reconstruction project as the background，a finite element analysis model of the dynamic response of high rock cutting slope under the load of explosion was established and the explosion¢s influence on the dynamic stability of upper bench slope during the excavation of lower bench slope with different blasting design parameters and different slope design types was discussed. The results of the detailed research indicated that the particle vibration velocity of slope strikingly decreased when using cushion blasting technology and suitable design degree of slope，and the influence of blasting on the cutting slope stability was effectively controlled.

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STUDY OF DISPLACEMENT BACK ANALYSIS OF ELASTO-VISCOPLASTIC PARAMETERS OF ROCK SLOPE

TAN Wanpeng，ZHENG Yingren

2010, 29 (S1): -2993 doi:
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[PDF 256 KB] (740)

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Based on complex variable differentiation method and according to the basic principles of the elasto- viscoplastic finite element analysis，Newton-Laplason iterative Optimized method is adopted with back analysis parameters and elastico-viscoplastic displacement by programme Fortran. With displacement of the key monitoring points，both strength parameters and creep parameters are back analyzed efficiently and accurately. Two examples verified the method¢s feasibility.

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STUDY OF INFLUENCE OF DEEP PIT EXCAVATION ON ADJACENT BRIDGE FOUNDATION PILES

WANG Cui1，YAN Shuwang1，ZHANG Qibin2

2010, 29 (S1): -3000 doi:
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[PDF 752 KB] (988)

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Based on the practical experiences，elastoplastic model is established by adopting finite differential method. Modified through monitoring data，the model is used to simulate the process of excavation and to analyze the mechanism of the influence on deep foundation induced by pit excavation. Furthermore，three effective controlling measures are presented for reducing the influence.

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SOME PROBLEMS ON DYNAMIC REPLACEMENT METHOD
TO IMPROVE SOFT SOIL GROUND

BAI Bing1，XU Huaxuan2，LIU Haibo2，FAN Qianghui2

2010, 29 (S1): -3006 doi:
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[PDF 225 KB] (922)

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Based on field tests and theoretical analyses，some problems on the dynamic replacement method(DRM) to improve saturated soft soil ground are discussed. These problems include the validity of soils for the DRM，the construction processes and the demands of filling，the evolution of pore water pressure and affecting scopes. Besides，the lateral displacements and deep settlements of soil layers induced by the squeezing effects due to dynamic replacement are also discussed. The formation processes of block stone column and its mechanism with the number of dynamic loading increasing are analyzed. Finally，the variation of bearing capacity of the soft soil foundation improved by DRM is investigated.

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EXPERIMENTAL STUDY OF A NEW WELDED JOINT OF STEEL DIAGONAL BRACING IN DEEP PIT EXCAVATION

GUO Haizhu1，2，ZHANG Qinghe1，2，REN Xiaofeng1，2，YANG Junlong3，YANG Guanghui3，XU Zhihua3

2010, 29 (S1): -3014 doi:
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[PDF 509 KB] (1028)

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A new welded joint of steel bracing is proposed. This new joint can be fixed soon after excavation without second welding，which can be rotated in some degree and can be prestressed. These measures can overcome the disadvantages of traditional welded joint，i.e. time increase of deep foundation exposure when using welding joints of diagonal bracing，inconvenient fixation of the slant angle immobility of diagonal bracing，and the prestress not being born on diagonal bracing after welding. It makes the time-space effects on deep foundation excavation obviously being reduced in soft clay areas. The bearing capacity of welded joints is studied by static load test on a welded steel rack with the same size. The test results reveal that the bearing capacity of the welded joint satisfies the requirements of design with a load of 2 500 kN. The whole structure remains stable only with some parts of the welded joint being yielded when load reaches 3 000 kN，and local concrete ahead of the embedded steel plate is crushed. The performance of the welded joint in the process of loading is simulated by finite element method(FEM). The calculation loading curve is consistent well with the test. The new welded joint of diagonal bracing can be used widely in deep foundation excavation with further processing.

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STRESS-STRAIN RELATIONSHIP OF STIRRUP-CONFINED CONCRETE SUBJECTED TO FREEZE-THAW CYCLES

DUAN An，QIAN Jiaru

2010, 29 (S1): -3022 doi:
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[PDF 766 KB] (973)

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In order to investigate the stress-strain relationship for stirrup-confined concrete after freez-thaw cycles，two series of concrete specimens(150 mm×150 mm×450 mm) with stirrup characteristic values of 0.317 and 0.145 respectively were exposed to rapid freeze-thaw cycles in water according to GBJ82–85. The axial compressive loading tests were carried out to obtain the complete stress-strain curves of confined concrete. Test results of 46 specimens show that，with the increase of freeze-thaw cycle number，the complete stress-strain curve becomes more flat，the peak stress decreases and the peak strain increases；with the same number of freez-thaw，the reduction of the peak stress and the increase of the peak strain are more serious for lower strength concrete. Moreover，damage appears at the bonding interface between stirrups and concrete due to freeze-thaw action，and the confining effect of the stirrups is weakened for lower strength concrete. Based on the test results，theoretical complete stress-strain curve equations for confined concrete subjected to freeze-thaw cycles are established. The equations could be used for nonlinear analysis of reinforced concrete structural elements experienced to freeze-thaw cycles in cold regions.

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MODEL TESTS OF PILE GROUPS IN CALCAREOUS SANDS

JIANG Hao1，WANG Ren2，LU Yinghui2，MENG Qingshan2

2010, 29 (S1): -3028 doi:
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[PDF 269 KB] (933)

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Calcareous sand is a special marine geomaterial medium，which has unexpected physico-mechanical properties due to its origin and fabric. The traditional practice，successfully used for other types of materials，is proved to be ineffective when used for pile foundations driven into calcareous sands. Model pile tests are carried out in a cylindrical testing chamber to investigate the bearing and deformation characteristics of pile groups in calcareous sands，which are taken from the Yongshu coral reefs in Nansha Islands in South China Sea. In contrast to the tests with silica sands，it is shown that calcareous sands behave in a completely different manner than silica sands due to grain crushing. Relative density has effect on the bearing capacity of pile group in calcareous，and the bearing capacity of close-ended pile group is 17%–20% larger than that of open-ended pile group，but it is less than that in silica sands. The axial force of pile group in calcareous sands has a slow decay rate，and the ultimate shaft friction of pile group in calcareous sands is only 21%–30% of that in silica sands，which is effected by depth，and it is very sensitive to density in silica sands but less in calcareous sands. In addition，when Dr = 46% and 75%，the bearing efficiency of pile group in calcareous sands is less than 1，and it increases with relative density，which is completely different from silica sands. The conclusion drawn from the study can provide valuable references for the practice.

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MODIFICATION OF DRUCKER-PRAGER CRITERION IN TENSILE SHEAR REGION

LI Ping¢en1，YIN Youquan2

2010, 29 (S1): -3033 doi:
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[PDF 267 KB] (1069)

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Drucker-Prager criterion(D-P criterion) has been widely used in the field of rock plastic mechanics. However，it is a type of compression shear yield criteria and not suitable for tensile shear stress states. According to this case，two feasible schemes are proposed to modify D-P criterion in tensile shear region. The first scheme is that the conical surface expression is still retained in compression shear region while in tensile shear region and its neighbor，a spherical yield surface is employed in place of the original conical surface near cone apex. The second scheme uses a hyperbolic rotating surface to approximately replace D-P conical surface. The modified new criteria defined by the two methods are called as D-P-Y criterions. They are three-parameter criteria and not only agree with the experimental result in triaxial compression test in compression shear stress states，but also can fit the tensile strength date in tensile shear regions. Meanwhile，the D-P-Y criteria are everywhere-smooth regular functions in all compression shear and tensile shear regions，and the constitutive equations can be established by using classic normality rule as well as consistency condition，needing no treating any singular points specially，which brings conveniences for application and programming. Particularly，for hyperbolic type D-P-Y criterion，when the relevant parameters are zero，it can be degenerated into D-P and Mises criterion，respectively. Therefore，it can be incorporated into D-P-Y criterion only in programming.

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OPTIMIZATION DESIGN OF CONNECTION METHODS OF DOUBLE-ROW ANTI-SLIDE PILES TIP

SHEN Yongjiang1，2，SUN Hongyue1，SHANG Yuequan1，WANG Yingchao1，YAN Kewu3

2010, 29 (S1): -3038 doi:
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[PDF 226 KB] (868)

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Based on the finite element program ANSYS，a finite element model with double-row anti-slide piles was established. The piles tip connection methods for the lateral displacement are analyzed，including bending moment and shear stress of piles，and the optimal piles tip connection. Piles tip connection methods include no connection，the row connection，the front-and-back rows connection and all connection. Compared with the four methods，it can seen that the front-and-bank rows connection is optimal. Using the front-and-bank rows connection and all connection methods，the double-row piles have better anti-slide effect. But using the all connection，the cost of anti-slide piles will increase. Two engineering examples which are respectively the row connection and the front-and-back rows connection，are simulated. Through monitoring and analysis of the stresses and displacements of the piles，it is found that the results are consistent with that of finite element analysis. So the front-and-bank rows connection of piles tip joint in the design can be suggested.

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MODEL EXPERIMENTAL RESEARCH ON ANTI-SLIDING CHARACTERISTICS OF MICROPILES WITH CAP BEAM

SUN Shuwei1，2，ZHU Benzhen1，MA Huimin1

2010, 29 (S1): -3044 doi:
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[PDF 681 KB] (919)

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Based on the model experiments，the anti-sliding characteristics of micropiles with cap beam were studied. It was shown that，a hyperbolic function could be used to describe the relationship of load and lateral displacement of micropile head. Micropiles in the rear row were trend to be pull out and the cap beam is tilt during the loading process. It was shown by monitoring the soil pressure that pushing force acting on micropiles with cap beam was trapezoidal distribution，and the resistance force below sliding surface was inverted with triangular distribution. The soil pressure value was larger at micropile head and around sliding surface and smaller at the bottom of micropiles. The ratio of pushing force acting on the micropiles between the rear row and leading row was 1∶0.6. Micropiles with cap beam and smaller spacing of micropile have larger anti-sliding capacity，but under the same value of the acceptable displacement，there was not a big difference between the two structures in the experiment. The pile cap beam could restrain the lateral displacement of micropile head and reduce the bending moment of micropile body effectively，meanwhile produce a higher bending moment at the micropile head，thus some methods，i.e. installing an oversized casing in the top portion of micropile，constructing a larger pile diameter at the top，embedding the pile cap deeper and so on could be adopted reasonably in engineering practice.

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SIMULATION AND ANALYSIS OF ROCK ANCHORAGE FAILURE MODES BY FINITE ELEMENTS OF MARC

YANG Haiwei1，ZHU Shaorong2，LU Jiqiang3，SUN Jijun4

2010, 29 (S1): -3051 doi:
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[PDF 595 KB] (817)

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The rock anchorage，as especial form of tower foundation in transmission line，can fully utilize the mechanical capability of original rock，and it can provide good pull-resistance capacity. For gradual using this tower foundation in overhead transmission line，some electric power institutes have been completed some real rock anchorage model tests. Based on this real model test of the rock anchorage，different types of rock anchorages are adopted，which included single-anchorage and direct-anchorage by MSC.Marc，software based on the principle of finite element analysis(FEA). The rock anchorage failure modes in three different states of rock intensities including poor(class IV)，medium(class III) and good(class II) are analyzed. And the contrast was processed between simulated results and failure modes in electric power trade design criterion. The results indicate that the rock intensity is the main factor affecting failure modes. The failure mode in current design code does not agree with the fact，and the calculation results of the rock are too larger when considering pull-resistance capacity，which maybe insecure to rock anchorage foundation design. The new failure mode was proposed according to the actual failure mode. At the same time，the availability of MSC.Marc was substantiated for assistant resolving of practical problems in geotechnical engineering.

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TEST STUDY OF MECHANICAL PERFORMANCES OF ANCHORAGE ZONE OF PRESSURE DISPERSION ANCHOR CABLE STYLE

ZHANG Yong1，ZHAO Hongling2，ZHANG Xangyang1

2010, 29 (S1): -3056 doi:
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[PDF 301 KB] (982)

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The field tests are performed in the anchorage zone of pressure dispersion anchor cable style and the cables are reclaimed. The stress distribution state on the anchorage zone is observed and the equations of the strain and axial force on the anchorage zone are obtained. Field test and the theoretical analysis both show that the unique structure form is a determinant factor for its credible corrosion protection capability，and its bearing capacity and anchoring characters are entirely better than the traditional tension cable style. Otherwise，this cable style has the reclaimable function that has better problem-solving ability of cable overpass allowable scope and can be extensively used in the city foundation pit reinforcement engineering.

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NUMERICAL SIMULATION FOR CONCENTRATED LEAKAGE MONITORING OF ROCK-FILL DAM WITH HEAT PULSE METHOD

CHEN Jiang，ZHANG Shaojie，LIU Haowu

2010, 29 (S1): -3063 doi:
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[PDF 384 KB] (807)

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Based on the basic theory of temperature tracer method and combined with the temperature distribution characteristic of core rock-fill dam，the gradient method and heat pulse method were compared，which can verify the disadvantage of gradient method to monitoring the concentrated leakage of core rock-fill dams. So heat pulse method based on FBG(fiber Bragg grating) sensing system was proposed for concentrated leakage monitoring in core rock-fill dam. The mathematic model of conjugated heat transfer among porous media-heat source-FBG was proposed as a theoretical basis for this method. At first，the relationship among temperature rise，seepage velocity，and heating power was obtained by numeral simulation with ADINA software. Then numerical simulation for concentrated leakage in core rock-fill dam was executed to obtain the seepage velocity distribution of every monitoring section. According to the fitting formula among temperature rise，seepage velocity，and heating power， the numerical simulation for concentrated leakage monitoring was carried out by converting the seepage velocity distribution to temperature rise distribution. The results show that the new method can be applied to exactly locating the leakage position. The smaller the distance between sensing system and downstream face of core is，the better the monitoring effect is. The higher the concentrated leakage intensity is，the more obvious the difference of temperature rise is.

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DRAINAGE-PROMOTION EFFECT OF AERATION VACUUM RAPID MUD-WATER SEPARATING TECHNIQUE ON DREDGED SLUDGE

ZHOU Yuan1，2，GAO Yufeng1，2，TAO Hui1，2，CHAI Yongjin1，2

2010, 29 (S1): -3070 doi:
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[PDF 264 KB] (855)

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Discarding the dredged sludge in the yard as waste material occupied much land，the aeration vacuum rapid mud-water separating(AVMWS) technique is suitable for discard yard with high water content and high clay particle content sludge. This technique can quickly reduce the volume of the sludge and accelerate the turnover use of the yard. More important，the technique can solve the clogging problem when pumping water from high water-content，high-clay particle content dredged sludge. Using the AVMWS technique in laboratory model test device developed by the authors，the conclusion that AVMWS technique has drainage-promotion effect on the water in sludge is drawn through the comparison of AVMWS laboratory model test and natural standing sedimentation laboratory model test. This technique can pump out much water from the dredged sludge through the filter tubes very quickly，and make the generating speed of water on the surface of sludge faster than that in natural standing sedimentation test. AVMWS technique has two drainage surfaces，and pore water seepage flows between the soil particles. Seepage generates relative flow between the solid phase and liquid phase. The relative flow makes soil particles suffering a certain tow force，and the tow force and its direction are related to constant velocity interface of relative flow. The tow force produces the process of cement-fracture compression and the rarefy effect，which make the sludge frame¢s volume compression speed faster than the speed of pump-out volume of pore water. Thus the mechanism of drainage-promotion effect of AVMWS technique has been explained.

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RESEARCH ON 3D DYNAMIC NONLINEAR ASEISMIC CALCULATION OF PILE GROUP FOUNDATION OF NORTH TOWER OF
TAIZHOU BRIDGE

QI Yuliang，FENG Ziliang，YU Jun，LIU Cheng

2010, 29 (S1): -3081 doi:
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[PDF 556 KB] (1319)

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The coupling numerical method，8-node three-dimensional isoparametric element with infinite element，was applied to the seismic response analysis of soil and bridge pile foundation. Based on the software of ABAQUS，the study sets up the corresponding calculation method and the great elastoplastic model of three- dimensional nonlinear time-history seismic dynamic response analysis concerning pile cap-pile group-soil system. The concrete damaged plasticity model was used for pile cap and pile，and the elastoplastic model of traditional Mohr-Coulomb yield criterion for soil. The unfavorable factors，which influence the bearing capacity of pile foundation，are taken into account，such as the natural self-weight of pile cap and large-diameter super-long bored pile，and the seismic liquefaction of saturated loose sand layer of shallow-buried river-bed around the bridge-pile construction site. The study puts forward the conception of unified static and dynamic viscoelastic infinite boundary. Under the static and horizontal vibration loads applied to pile cap-pile group-soil system at the same time，what have been obtained by 4 CPUS¢ parallel calculation are the dynamic axial force，shear force and moment of pile group，the side friction and the contact pressure between pile shaft and the soil around pile，and so on. These are valuable results for the design and calculation. Furthermore，the calculation results give out an overall and deep understanding about the aseismic performance of bridge pile foundation.

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PUMPING TEST AND ITS APPLICATION TO DEEP FOUNDATION PIT UNDER COMPLEX MORE FLOW HYDROGEOLOGICAL CONDITIONS

WANG Jianxiu1，2，WU Lingao1，2，HU Lisheng2，LI Guo1，2，TANG Yiqun1，2，
YANG Ping1，2，XU Xu3，LOU Rongxiang3

2010, 29 (S1): -3087 doi:
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[PDF 282 KB] (897)

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Taking swirl pool deep pit，PU steel relocated project，Baoshan Iron and Steel Co.，Ltd.，as an example，the complex more flow of confined aquifer conditions is made clear through pumping test in field，and reasonable conception model is established. The design of deep pit dewatering with pumps inside and outside of pit is completed based on the conception model. The pumping test of well group verifies the reasonability of design，and the dewatering course indicates that the more flow conception model is reasonable，and the pit is dry during construction through the combined function of well group inside and outside of pit，which meets the control standard. In pumping test by opening two wells and resting one well，leakage of concrete wall is predicated and emergency measure is prepared. When the leakage of concrete wall emerged，reasonable measures were adopted in time and serious accident was avoided. The research results can provide a reference to similar project.

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EXPERIMENTAL STUDY OF SHEAR CREEP CHARACTERISTICS
OF LOESS

WANG Songhe，LUO Yasheng，DONG Xiaohong，FU Zhongyuan

2010, 29 (S1): -3092 doi:
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[PDF 283 KB] (860)

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By taking the Q3 loess of Yangling district in Shaanxi province as the research object，a direct shear creep test is conducted to investigate the characteristics of creep behavior of intact loess，disturbed loess and saturated loess. The experimental results indicate that the intact loess，the disturbed loess and saturated loess all have creep characteristics；under the same experimental conditions，the creep strain rate of saturated loess is the fastest and the creep strain is the biggest among the three kinds of loess samples. The creep characteristics of disturbed loess is less obvious than that of saturated loess；and it is least obvious in intact loess. According to the characteristics of creep curves，a new logarithm model is suggested；and based on the typical creep behavior of loess，the fraction-linearity creep model is used to simulate the shear creep characteristics of Yangling Q3 loess according to the fitting results，the parameters of model are obtained；the model better simulates the creep characteristics of Q3 loess in Yangling district by model test. Besides，based on the experimental data，the relation between shear modulus and normal stress and time is fitted，and a new method to confirm the shear elastic module is supplied.

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STUDY OF STABILITY CHARACTERISTICS OF MULTI-STAIR HIGH CUT SLOPE IN LOESS HIGHWAY

HU Jinchuan1，XIE Yongli1，WANG Wensheng1，2

2010, 29 (S1): -3100 doi:
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[PDF 650 KB] (771)

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In order to study the stability characteristics of the multi-stair high cut slope in loess highway，the centrifugal test was carried out based on loess slope engineering of Yanliang—Yumenkou highway，and numerical analysis method was used to analyze the stability behavior of multi-stair high cut slope by ANSYS program modeling，including the deformation process，destruction character，and stability characteristics. The results show that the lateral deformation will occur before the damage of multi-stair low unsaturated loess slope，and the maximum horizontal displacement appeared in 1/3 slope height and from 2/3 slope toe，and the characteristic of slope deformation is vertical firstly，and then horizontal. When the lateral deformation of unsaturated loess slope appears，there is a very short region of no horizontal strain in the loess slope. The stability of multi-stair-low slope is mainly controlled by macro-ratio of slope，but there is no influence of secondary low slope on high slope stability. Multi-stair-low slope，where inclination is above 70°，can eliminate the surface washing out by upstanding characteristic of loess. Therefore，the water infiltration is increased and the runoff generation is decreased. A good site condition is created for the protection of plant growth. Multi-stair-low slope is a well form in slope engineering of loess area highway，which has good engineering and application values.

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CENTRIFUGAL MODEL TESTS ON SELF-WEIGHT COLLAPSIBLE LOESS AND NEGATIVE SKIN FRICTION OF PILE FOUNDATIONS

(1. Key Laboratory of Road and Traffic Engineering of Ministry of Education，Tongji University，Shanghai 201804，China；
2. School of Civil Engineering，Lanzhou Jiaotong University，Lanzhou，Gansu 730070，China)

2010, 29 (S1): -3107 doi:
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[PDF 284 KB] (964)

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Collapse settlement，collapsibility of self-weight collapsible loess and negative skin friction of pile foundation are crucial issues in the basic research of collapsible loess ground. The centrifugal model test is used to simulate the immersion test with undisturbed and remolded collapsible loess foundations，to research and analyze the collapsibility of loess and negative skin friction of pile foundations. The research results show that the processing of undisturbed and remolded loess collapsibilities can mainly be divided into three stages，which are the stages of significant of collapsible deformation，stabilization stage of collapsible deformation and soil consolidation deformation stage after the dropping of water level. The method of centrifugal model test which uses remolded collapsible loess instead of undisturbed collapsible loess to research the self-weight loess collapsibility is practicable for the purpose of settlement study by analyzing the test data. Then the changing laws of negative skin friction and the position of neutral point are concluded. The movement of negative skin friction and the position of neutral point are a continuous changing process. The ratio of the neutral point position to length of pile is in the ranges of 0.68–0.82.

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RESEARCH ON LATERAL STRESS-STRAIN RELATION ON SIDE OF FOUNDATION PIT WITH LATERAL UNLOADING

MEI Guoxiong1，CHEN Hao1，LU Tinghao2，YIN Zongze2

2010, 29 (S1): -3112 doi:
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[PDF 183 KB] (807)

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Taking soil on the side of foundation pit excavation with consolidation-lateral unloading plane strain experiment on plane strain apparatus，the testing results indicate that the shear strength indices of soil are obviously different between the lateral unloading and routine triaxial tests. Experimental analyses show that curves of lateral stress-strain under lateral unloading are also similar to a hyperbolic type. The lateral stress-strain relation of actual stress path and lateral unloading soil on the side foundation pit is deduced using Duncan-Chang model. Results between experimental data and model predicated are coincided very well.

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EXPERIMENTAL STUDY OF STORAGE-VARIABLE TRANSIENT PULSE METHOD FOR PERMEABILITY MEASUREMENT

WANG Ying，LI Xiaochun，WEI Ning

2010, 29 (S1): -3121 doi:
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[PDF 365 KB] (787)

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Based on the storage-variable transient pulse method and its experimental arrangement，the limitations of the old arrangement in measuring range have been discussed. As a result of the shortcomings，the old arrangement has been modified perfectly. The validity and repeatability of storage-variable transient pulse method have been improved greatly by using the new arrangement. The storage varied range of the new storage-variable apparatus has been testified over 10－2–102 mL/MPa，by making the repeatability experiments for one and the same sample at multi-order apparatus storages. The appropriate measuring range of the new experimental arrangement has been confirmed between 1 mD and 1 D，as well as the proper measuring time during 10 s–2.5 h，moreover，the new arrangement performs satisfactorily showing from high repeatability which is less than 5%. The test results show that the relations among specific storage of apparatus，decay time and permeability obtained from tests in accordance with those shown from theory. Small storage of apparatus can shorten measuring time，whereas large storage will prolong testing time. That is to say，small storage for impermeable sample and large storage for high-permeable one should be selected. Thus it is clear that many kinds of rocks with different permeabilities and also those permeabilities varied widely can be measured efficiently by using transient pulse method experimental arrangement，thereby a broad application prospect will be looked forward.

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APPLICATION OF HILL¢S STABILITY CONDITION TO BEARING CAPACITY COMPUTATION OF FOUNDATION WITH FINITE ELEMENT METHOD

WANG Lizhong1，SHU Heng1，2

2010, 29 (S1): -3131 doi:
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[PDF 542 KB] (1229)

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Based on the secondary development of ABAQUS，the Hill¢s sufficient stability condition is applied，with finite element method，to limit bearing capacity calculation of strip foundation on cohesive frictional soils. The limit bearing capacity of the foundation as well as the potential instability regions of the soil is studied. According to Hill¢s sufficient stability condition，when the local second order work of the soil system is negative，the local region becomes potentially instable；when the global second order work of the system is negative，the system arrives limit state，and becomes potentially instable，thus the limit bearing capacity of the system is the load applied to the system at the moment. The influence of dilatancy angle on the bearing capacity is studied. Results show that，when the dilatancy angle is much smaller than the frictional angle，the limit bearing capacity computed by finite element method(FEM) with Hill¢s sufficient stability condition is close to theoretical solution of the equivalent material，and smaller than that of regular FEM. When the dilatancy angle is close to the frictional angle，the results of FEM with Hill¢s sufficient stability condition and the regular FEM are close and both can give preferable solution. The FEM with Hill¢s sufficient stability condition can also give the potential instability regions of the soil system，which can depict the surface failure mode and field failure mode simultaneously. Since the FEM with Hill¢s sufficient stability condition has a solid and clear theoretical background and therefore it is convenient to use，it is a deserved method for recommendation.

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FAILURE PATTERN STUDY AND SECURITY ANALYSIS OF TUNNEL AFFECTED BY PILE LOAD

QIU Chenyu1，ZHENG Yingren1，SONG Yakun1，GE Suming2，YUAN Yanren3

2010, 29 (S1): -3144 doi:
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[PDF 435 KB] (732)

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The stability analysis of Chaotianmen Tunnel affected by pile load is carried out by strength reduction finite element method. Interaction between pile and tunnel is a complex procedure of pile-soil-structure interaction. It contains three kinds of failure patterns：tunnel failure，pile foundation failure and lining failure. Tunnel failure and pile foundation failure are shear breakage of soil. The safety factor can be calculated by strength reduction finite element method. Six kinds of calculation schemes and sixteen kinds of pile positions are established，in order to study the influence factors of stability of tunnel by pile loading such as strength of rock mass，pile load，distance between pile and tunnel，depth of pile，etc.. Through analyzing the calculation result of safety factor，it is found there are critical distance and critical depth between tunnel and pile. Pile has greatly influence on tunnel，if it is located within critical distance or critical depth，and tunnel will fail firstly. Conversely，pile has little influence on tunnel，and pile foundation will fail firstly.

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STUDY OF DILATANCY EFFECT OF REDSTONE COARSE GRAINED
SOIL BY LARGE SACLE TRIAXIAL TESTS

CHEN Xiaobin1，2

2010, 29 (S1): -3149 doi:
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[PDF 223 KB] (1037)

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In order to study the dilatancy effect of granular soil and effects on the dilatancy tendency under different confining pressure conditions，a series of red stone granular soils tests are executed by the large scale triaxial shearing apparatus. The test results show that the confining pressure has obvious effects on the dilatancy effect of granular soil，and the different dilatancy effects are observed from the different confining pressure tests. When the confining pressure is less than 200 kPa，the ratio of volume increment to axial strain(dev/de1) is negative，which shows dilatancy tendency. When the confining pressure exceed 400 kPa，the ratio of volume increment to axial strain(dev/de1) is positive，and the red stone granular soil samples shows shearing shrinkage tendency in the tests. The red stone granular soil dilatancy tendency is also changed by the axial strain increment，with firstly quick dilatancy tendency and then slow dilatancy tendency. The coefficient K of Rowe shearing dilatancy model is obviously discrete during the shearing procedure，which reflects the deformation incompatibility between the coarse grains and fine grains in red stone granular soil. The discrete degree is minishing with the total axial strain increment. The shearing dilatancy coefficient K of Rowe is identified as 20–25 for the red stone granular soil in these test data.

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EXPERIMENTAL STUDY OF A NEW POLYMER GROUTING MATERIAL

LI Liping1，LI Shucai1，ZHANG Qingsong1，CUI Jinsheng2，XU Zhenhao1，LI Zhao2

2010, 29 (S1): -3156 doi:
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[PDF 265 KB] (1149)

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In order to find the proper grouting material for treatment of water inrush and rock reinforcement in deep underground engineering，the feasibility of a new polymer grouting material is analyzed. The experimental properties of cohesion，gelation，strength and virulence of the new polymer grouting material are studied in the laboratory. It shows that this new polymer grouting material is of high fluidity，strong adhesion and durability，comparing with other types of grouting material. It has advantages on convenient storage and transportation，simple and practical grouting technology，non-poisonous and water-expanding property. In addition，by the grouting simulation test in sandy gravels，the influences of grouting pressure，grouting time，permeability coefficient，porosity upon grout diffusion radius，concretion strength and their correlation were analyzed. The grout diffusion radius increased with the increasing of grouting pressure，grouting time and permeability coefficient，and decreased with grout temperature. Distinct influencing factors on grout diffusion radius were grouting pressure and permeability，but the influences of grout temperature and grouting time were small. Strength of grouted gravels increased with the increasing of grouting pressure，grouting time，porosity and grout temperature. The results show that the new polymeric grouting material has rapid gelation，high strength and effective dilation，comparing with traditional solidified ones，which is a better polymeric grouting material for the treatment of water inrush and engineering reinforcement.

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TEST STUDY OF COEFFICIENT OF CONSOLIDATION OF FRESH
HYDRAULIC FILL ULTRA-SOFT SOIL IN SHENZHEN BAY

ZHANG Ming1，ZHAO Youming2，GONG Lei3，HU Ronghua1

2010, 29 (S1): -3161 doi:
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[PDF 246 KB] (1215)

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Automatic pressure consolidometer is introduced to conduct numerous consolidation tests of hydraulic ultra-soft soil filling in Shenzhen Bay，and results are analyzed statistically and compared with coefficient of consolidation of original mud. The obtained results verify that：(1) In actual engineering，coefficient of consolidation is introduced to estimate the deformation and rate of consolidation of hydraulic mud filling approximately in special zone，which is confined within a statistical sample average curve in stress range(less than 100 kPa) and a logarithm function-width in stress range(more than 100 kPa). (2) Consolidation coefficient of hydraulic mud filling is less than original mud in a same zone，with an increase in consolidation pressure，the difference becomes small. It shows that hydraulic mud filling can be achieved a same drainage consolidation rate with original mud after it experiences surcharge preloading.

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THRUST SHARE RATIOS AND OPTIMIZATION DESIGN FOR TWO-ROW
ANTI-SLIDE PILES

TANG Fen1，2，ZHENG Yingren2，YANG Bo2

2010, 29 (S1): -3168 doi:
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[PDF 210 KB] (1094)

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The structure of two-row anti-slide piles is a complex mechanical characteristics. A finite element model is established and the share ratios with the thrust of the front and back rows of piles at different row distances are discussed. It indicates that the total thrust of the two-row piles is bigger than the thrust of only the front row piles. While the row distance is small，the back row pile shared almost all the thrust，and with the masking function of the back row piles，the front row pile couldn't display the best effectiveness. When the pile row distance increased，the share ratio of piles in front row increased gradually. The two piles worked independently，resisted part sliding block respectively and displayed the best effectiveness at the particular row distance. Based on calculation of trust and stability factor for the structure of two-row anti-slide piles，the projects of the total trust，the stability factor and the difference of two piles are selected and the multi-project optimization for two-row anti-slide piles is put forward. The most reasonable row distance and share ratio of the thrust are attained.

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CALCULATION STUDY OF RANKINE EARTH PRESSURE BASED ON UNIFIED STRENGTH THEORY

ZHANG Jian1，2，HU Ruilin1，LIU Haibin3，WANG Sansan1

2010, 29 (S1): -3176 doi:
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[PDF 243 KB] (1011)

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The issue of wall earth pressure will be regarded as problem of plane strain，so intermediate principal stress is calculated by generalized Hook¢s law in plane strain assumption. The principal stress in accordance with the principle of Rankine earth pressure is determined. On this basis，the formula of Rankine earth pressure is derived when the expression of principal stress in double-shear unified strength theory is used. The weighted coefficient b considering effects of intermediate principal stress and the Poisson's ratio is introduced to the formula. The solution based on classical Rankine active earth pressure theory is a special case of the unified solution. The unified solution can be flexibly used to calculate earth pressure of various filled materials. Finally，an example is given to show the impact of their results in different weighted coefficients b. The analytical shows that the result of classical Rankine passive earth pressure theory is smaller，so it often causes the potential danger. However，the result of classical Rankine active earth pressure theory is larger and has enough safety storage. The potential strength of filling materials is sufficiently developed under the guidance of the double-shear unified strength theory，so some economic benefits can be obtained.

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STABILITY ANALYSIS OF EXCAVATION AND LINING STRUCTURE OF LARGE-SPAN TAILRACE BIFURCATION TUNNEL

LIN Peng1，ZHOU Yaneng1，ZHU Xiaoxu1，WANG Renkun2，ZHAO Wenguang2

2010, 29 (S1): -3183 doi:
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[PDF 379 KB] (958)

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The current research situation and commonly used method of stability for excavation and lining of large-span tailrace bifurcation tunnel at home and aboard are reviewed. Based on summary studies，an evaluation method to analyze the stability of excavation and lining structure is proposed. It involves the basic principles of numerical method，analytical contents，flow charts and evaluation index. By employing this evaluation method，the tailrace bifurcation tunnel of Xiluodu hydropower station is analyzed，including the distribution characters of deformation，stress and yield zone in the surrounding excavated rock mass and the reinforcing effect under different stress releasing conditions. The deformation and stress state in surrounding rock mass and lining structure also are investigated under operation and maintenance loading conditions. The numerical results and monitoring results are consistent. Based on the numerical results of practical projects，it shows that the proposed evaluation method related to tailrace bifurcation tunnels can be applied to the design and construction of the similar projects.

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NUMERICAL ANALYSIS OF DEFORMATION OF DEEP EXCAVATION ADJACENT TO METRO CONSIDERING SMALL-STRAIN STIFFNESS OF SOIL

CHU Feng1，2，LI Yongsheng1，LIANG Fayun1，LI Yandong1

2010, 29 (S1): -3192 doi:
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[PDF 391 KB] (1237)

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Based on a case of deep excavation adjacent to metro station in Shanghai City，a two-dimensional finite element model to analyze this typical problem is proposed. Small-strain stiffness of soil is considered to investigate the deformation characteristics of deep pit excavation adjacent to metro station. The calculation data show that the deflection of retaining wall is obviously reduced when the small-strain stiffness of soil is considered in numerical analysis. And it is much close to the observed results. As for the deep pit excavation adjacent to metro station，the excavation sequences have obvious influences on the deformations of retaining wall. Numerical results also show that excavating big parts of the pit foundations firstly can reduce the deformation of retaining wall effectively than that of excavating small parts in advance. The results are consistent with the practical experiences in Shanghai area. The conclusions have some instructions for the designs and constructions of similar engineering.

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ANALYSIS OF TOPPLING FAILURE OF ROCK SLOPES DUE TO EARTHQUAKES

LIU Caihua，CHEN Congxin

2010, 29 (S1): -3198 doi:
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[PDF 1242 KB] (782)

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Toppling is an important failure mode of rock slopes，which is dominantly controlled by the discontinuities existing in the slopes. Adopting the concept of the transfer coefficient，an analytical approach of toppling failure of rock slopes due to earthquakes is developed based on the corresponding geomechanical model，and influence of seismic actions on the toppling stability of rock slopes is analyzed. The variables of every rock block potential to toppling，used for stability analysis of a rock slope，are expressed by the geomechanical parameters of the slope and the serial number of the blocks，and hence have uniform expressions. Consequently，the method is easily implemented using a Microsoft Excel spreadsheet. An idealized example is analyzed adopting the Excel procedure. The results show that the failure mode of a rock slope，such as sliding or toppling，depends on the relationship between the seismic influence coefficient and its critical value which is determined by the direction of the seismic force，the dip angle and the friction angle of the slightly dipping discontinuities. The rock slope is potential to topple if the seismic influence coefficient is less than the critical value，or it will slide. It is also indicated that the toppling stability of rock slopes increases slightly with the angle of the seismic force with respect to the horizontal plane rising but descends markedly with the seismic coefficient increasing.

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EXCAVATION DISTURBANCE AND ITS INFLUENTIAL FACTORS ON MATERIAL-YARD SLOPE OF GUANDI HYDROPOWER STATION IN YALONG RIVER

TIAN Bin1，LU Xiaochun2，HUANG Yaoying1，JIANG Dingguo1

2010, 29 (S1): -3207 doi:
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[PDF 359 KB] (837)

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Excavation disturbance is an important factor for engineering slopes stability，and it runs through the whole process of slope excavation. The excavation disturbance and influential factors are researched combined with the material-yard slope of left bank of Guandi hydropower station in Yalong River. Based on the analyses of slope instability mode and mechanical parameters of the rock mass，the nonlinear finite element analysis for typical slope segment including excavation process is carried out，and the excavation disturbance characters and the influential effects of slope are also obtained. The excavation disturbance includes the stress，displacement，equivalent plastic strain，etc.，and the influential effects are the parameters of the joint crack and the rocks fault，anchoring method，etc.. And then，the suggestions for reinforcement scheme of slope stability during construction period and long-term operation are proposed. The results show that the construction schemes of excavation by steps and reinforcement by steps are effective for slope stability. Anchorage supports can not only restrain deformation effectively，but also can control strength loss. Bases on the achievements，some suggestions of excavation and reinforcement scheme are presented for practical engineering. As an important case of hydropower project，the results can also be used in the treatment of excavation slope in railway construction，highway construction and open-pit slope.

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THREE-DIMENSIONAL NUMERICAL ANALYSIS OF TRAVERSING AND TWISTED FRACTURES IN HYDRAULIC FRACTURING

LI Lianchong，LIANG Zhengzhao，LI Gen，MA Tianhui

2010, 29 (S1): -3215 doi:
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[PDF 1012 KB] (1636)

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Numerical tests with parallel finite element method(FEM) are conducted to investigate the hydraulic fracturing. The fracture initiation，propagation and associated traversing，twisted fractures are numerically obtained，which indicate that the finite element model has potential applications to a larger range of complicated hydraulic fracturing problems. As the proposed method is used to conduct the numerical simulation of hydraulic fracturing，the three-dimensional fractures can be achieved directly without any artificial assumption on the initiation and propagation of fractures. Numerical results，including the pore pressure field，fracture shape and size，show that the mechanical parameters of strata have an important influence on the fracture mode. The traversing fractures are prone to emergence if the producing zone is thin or the difference of rock mechanical parameters is relatively great. The traversing fractures are prone to induce the failure of hydraulic fracturing. The twisted fractures are mainly caused by in-situ stress distribution，stratum characteristic and the heterogeneous characteristics of rock at mesoscopic level. The investigation can provide significantly meaningful guides for the design of hydraulic fracture engineering in practice.

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LOOSENING ZONAL MODEL AND ITS APPLICATION TO BACK ANALYSIS OF UNDERGROUND ENGINEERING

CHEN Qiuhong1，2，LI Zhongkui1，ZHANG Zhizeng1

2010, 29 (S1): -3220 doi:
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[PDF 243 KB] (923)

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Due to blasting and other disturbances during the process of excavation of underground caverns，loosening zone around the caverns can be found，and it would become larger with time at high geostress. Several loosening zone models and its simulation method proposed are introduced by other scholars. Based on the models， a new model is proposed that is related to frequency and displacement，which can be used to large and complex underground caverns. Due to different forms and distribution loosing zones around the underground caverns，its application to displacement back analysis for Jinping I hydropower underground caverns is introduced. Therefore，it should consider loosening zone in back analysis，and the proposed loosening model is suitable for underground engineering.

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PREDICTION OF SURROUNDING ROCK CLASSIFICATION IN ADVANCE BASED ON TSP203 SYSTEM AND GA-SVM

QIU Daohong，LI Shucai，ZHANG Lewen，XUE Yiguo，SU Maoxin

2010, 29 (S1): -3226 doi:
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[PDF 345 KB] (852)

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In order to conduct surrounding rock classification ahead tunnel advancing effectively，the advanced surrounding rock classification method based on TSP 203 system and genetic algorithm(GA)-support vector machine(SVM) is put forward. The method extracts the useful information from the detection results of TSP 203，and it establishes the indicators system of advanced surrounding rock classification. In the progress of establishing advanced surrounding rock classification index system，six rock classification parameters are adopted，which TSP203 could identify effectively，i.e. rock mass integrity coefficient，Poisson¢s ratio，static Young¢s modulus，the angle between main structural surface and the tunnel axis，discontinuous structural surface and the state of groundwater. GA was adopted to optimize the SVM parameters in solution space，which improves the discrimination precision of SVM in surrounding rock classification. Finally，the method is applied to practical engineering and the results show that the method has higher prediction accuracy in predicting advanced surrounding rock classification and provides a new idea for advanced surrounding rock classification.

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LONG-TERM STABILITY ANALYSIS OF DABAN DIVERSION TUNNEL BURIED IN SWELLING MUDSTONE

DAI Yonghao1，CHEN Weizhong1，YU Hongdan1，ZHANG Yuelin2

2010, 29 (S1): -3234 doi:
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[PDF 1242 KB] (745)

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Combining with the triaxial creep test and numerical simulation，the creep characteristics of the saturated swelling mudstone of Daban diversion tunnel are studied，and the nonlinear constitutive relationship of mudstone is put forward by fitting with the triaxial creep test results. The numerical simulation considering the tunnel¢s excavation，supporting and operation is also carried out. More attention is paid to the simulation of overbreak with tunnel boring machine(TBM)，the shield lining segment¢s cracking，failure，and the tunnel¢s long-term stability after supporting，which include with bolting，injection，secondary lining and steel bow member applied. In the end，the tunnel¢s long-term stability is evaluated，and the supporting design of the tunnel is verified. The gained results can provide the basis for the tunnel¢s support design of similar engineering projects.

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EXPERIMENTAL RESEARCH ON HYDRAULIC BEHAVIORS IN A SINGLE JOINT WITH VARIOUS VALUES OF JRC

HE Yulong1，TAO Yujing2，YANG Lizhong1

2010, 29 (S1): -3240 doi:
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[PDF 328 KB] (1246)

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Fluid flow through rock joints is commonly described by the smooth parallel plate model，which includes cubic law. However，the real rock joint surfaces are rough，and the fluid flow through a single fracture is not always consistent with the cubic law. Based on the typical joint roughness profiles proposed by N. Barton and V. Choubey(1977)，the templates with different joint roughness coefficients(JRCs) are manufactured by using numerical control wire cut electron discharge machining，and then，ten single-fracture column concrete samples with various JRCs from 0 to 20 are produced(50 mm in diameter and 100 mm in height). The single fracture¢s permeability tests were conducted at various effective stresses using RCCP test system. The test results show that：(1) The JRC has significant effect on the permeability of a single joint under low effective stress，and the effect of JRC on the permeability of a single joint decreases rapidly with the increasing effective stress. (2) The relationship between the permeability and the effective stress of a single joint follows the law of negative exponent，showing an obvious nonlinear behavior. For a single joint，the rate of change in the permeability versus the effective stress under low stress level is greater than that under middle-high stress level. Moreover，under the low stress level，the permeability of a single joint has a trend of decreasing with the increase of JRC at the same effective stress conditions.

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DETERMINATION METHOD OF SUPPORTING TIME FOR SECONDARY LINING IN TUNNEL CONSIDERING ROCK CREEP BEHAVIORS

WANG Zhongwen1，2，FANG Jianqin2，3，4，XIA Caichu3，4，BIAN Yuewei3，4，JIN Lei3，4

2010, 29 (S1): -3246 doi:
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[PDF 197 KB] (1024)

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Tunnel deformation on the basis of rheological theory is discussed，followed by an exponential fitting of the field monitoring data. Three rheological parameters are then given. Using these three parameters，the appropriate supporting time of second lining is proposed according to the national specifications. Further more，the time of secondary lining in tunnels with different primary lining thicknesses as well as different excavation spans are given using these parameters.

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INVERSE PROBLEMS AND PREDICTION OF WATER INFLOW
IN TUNNELS OF JINPING II HYDROPOWER STATION

XIA Qiang1，2，WANG Xusheng1，POETER E2，WAN Li1

2010, 29 (S1): -3253 doi:
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[PDF 476 KB] (666)

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Jinping II hydropower station is situated in a karst area with mountains and valleys. The excavation of large size tunnels will significantly change the conditions for groundwater flow，causing inflow in the tunnels and impacts on surrounding environment. As indicated by the discharge patterns of groundwater in the auxiliary tunnel during its construction，12 fractured zones with high vertical conductivity are existing in the Jinping mountain. Five three-dimensional stead state flow numerical models are built with MODFLOW. In the models，these fractured zones are typically considered. UCODE is employed to calibrate the models according to observations of groundwater inflow，and key parameters are identified and optimized for better modeling. Based on the waterproofing technique in the auxiliary tunnel，the models predict water inflows in all tunnels before and after waterproof protections，and the results are 40.35 and 31.19 m3/s，respectively. Excavation of the tunnels will causes drying of two major springs in the area，and the springs could not be recovered unless more effective waterproof protection is applied.

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APPLICATION OF ANALYTICAL METHOD OF CRACK LINE FIELDS TO ROCK MECHANICS

WANG Cheng

2010, 29 (S1): -3258 doi:
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[PDF 184 KB] (646)

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The fractures of rock mass in engineering are originated from the cracks located in it，and the solution to stress fields in multi-crack body is one of the most difficult problems in fracture mechanics. The cracks on main- controlled surface in rock mass damage are regarded as uniformly-spaced collinear cracks. When the reasonable equations on crack line are applied，the problems of collinear multi-crack loaded by shearing- compressive stresses are simplified as the issues of a crack in finite-dimension rock. The methodology to solve this problem is yielding criterion of rock mass material. An analytic solution near the crack line in an elastic-perfectly plastic rock mass is obtained，when the line field analysis method is applied. The influence of frictional strength on crack surface towards the shearing-compressive stresses is analyzed，which results from closure of crack surfaces on the stress fields. By proposing the reasonable equations on the crack line and the matching conditions of the elastoplastic stress fields at their boundaries，the relations between the length of plastic zone on the crack line and shearing-compressive stresses are obtained. Also，the failure criterion of the rock mass with collinear cracks along the main-controlled surface is yielded. The correctness of the analysis method is verified by the experimental results of a model test. The study serves as an important basis for the development of rock mass fracture mechanics.

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ZHANG Mingjian1，2，GAO Jinhai2，WEI Shiyi1，CHEN Xinming1，CHEN Wuzhuang1

2010, 29 (S1): -3264 doi:
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[PDF 337 KB] (770)

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In deep mining，the effective roadway support is an important factor to ensure the safety mining，high production and efficiency. Based on the similarity simulation test and the field test，the fracture characters of the horizontal roadway are studied，which is located in deep tiled strata in Coal Mine No.8 of Hebi Coal Power Ltd.. The law of displacement of roadway，under different applying loads，and the characteristics of development of fracture in roadway and distributions are analyzed. For this geological condition，the more effective support plan is figured out. The study result can be used for understanding the occurrence，development and relationship of the surface of roadway and interior cracks. Based on the results，the support parameters of the roadway can be chosen reasonably. The study methods and results can be used as reference for other similar studies as well.

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MECHANICAL CHARACTERISTICS OF UNSYMMETRICAL SUPPORT STRUCTURE OF SHALLOW-BURIED BIAS MULTI-ARCH TUNNEL

WANG Yaqiong1，ZHANG Shaobing1，2，XIE Yongli1，LAI Jinxing1

2010, 29 (S1): -3272 doi:
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[PDF 505 KB] (1035)

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According to the issue of unsymmetrical force in the construction of shallow-buried bias multi-arch tunnel and the actual situation of Yaoshuixia multi-arch tunnel，the mechanical characteristics of shallow-buried bias multi-arch tunnel are analyzed using finite element method and in-situ monitoring，and the support structure is optimized with unsymmetrical design methods. The results indicate that the unsymmetrical design and construction of the shallow-buried bias multi-arch tunnel are feasible；the pressure on earlier constructed cavern of the multi-arch tunnel is greater than that of the later one，and the relation between this result and the bias condition is not obvious；the pressure on surrounding rock of shallow-buried bias multi-arch tunnel should be considered according to the radial load of the round cavern. Therefore，when designing and constructing the similar shallow- buried bias multi-arch tunnel，the construction sequence should be paid attention to，and the unsymmetrical design of the structure is feasible.

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EXPERIMENTAL STUDY OF STRENGTH EVOLUTION LAWS IN ROCK FAILURE PROCESS

ZHANG Houquan，HE Yongnian，ZHOU Jijun，HAN Lijun，JIANG Binsong，SHAO Peng

2010, 29 (S1): -3279 doi:
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[PDF 338 KB] (974)

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Rock material strength will degrade with the damage in rock failure process. This paper reports one self-designed method to test rock strength degradation and introduces the technical routine，sample preparation and its key technique in detail. Through self-designed direct shear tests，the relationships between shear stress and compressive stress of irregular damaged rock samples which are produced in common uniaxial and triaxial compressive experiments are obtained；and a Coulomb strength curve can be gained by the linear regression through compression-shear testing data. A comparison between the Coulomb strength curve and the ultimate Mohr circle envelope linearly-regressed by previous uniaxial and triaxial compressive experimental data is performed；and the evolution laws of material strength(cohesion and internal friction angle) in rock failure process are analyzed and discussed. The application scopes of two kinds of completely reverse evolution laws of cohesion and internal friction angle are clarified through the analysis and discussion. The research results show that the cohesion measured by uniaxial and triaxial experiments of intact rock samples is obviously greater than that obtained by direct shear tests of irregular rock blocks. This difference mainly resulted from the damage in rock failure processes of uniaxial and triaxial compressive experiments，not from the deviation between different testing methods. Cohesion reflects rock intrinsic strength characteristic，slightly influenced by different stress states. The internal friction angle obtained by uniaxial and triaxial experiments is smaller than that gained by direct shear tests of rock blocks. This difference mainly resulted from the influence of different stress states and rock flaw distribution. Internal friction angle increases rapidly to the maximum and decreases steeply to keep a certain stable trend in rock failure process. Internal friction angle reflects rock frictional strength characteristic，heavily influenced by different stress states. The sensitivity of cohesion to stress level is far lower than that of internal friction angle. The material strength itself degrades obviously before and after rock failure.

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ANALYSIS OF FRACTAL CHARACTERISTICS OF FRAGMENT FROM
ROCKBURST TEST OF GRANITE

LI Dejian1，2，JIA Xuena1，2，MIAO Jinli1，2，HE Manchao1，2，LI Dandan2

2010, 29 (S1): -3289 doi:
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[PDF 398 KB] (1055)

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Rockburst test of Laizhou granite is carried out under true triaxial experimental machine system with one surface of the sample unloading suddenly，and the rockburst fragments are collected. The rockburst fragments are measured including the mass，length，width and the thickness. The fragment quantities of coarse，medium，fine and micro grains in different size ranges，quality and particles distribution are analyzed also. Rockburst fragment fractal of the granite is obtained according to the relations of the fragment length，width，and thickness to cumulative number. Respectively，the relation of ratio of cumulative mass of equal length which is smaller than it divided by the total mass to equal length，as well as the relation of equal length to cumulative number of fragments. The results show that the degree of crushing of granite rockburst fragments is higher and with obvious slab characteristics. The micro-particles(approximately＜0.075 mm of rock sample after rockburst are analyzed by laser-particle machine. The most，moderate and smallest micro-particles mass of rock sample after failure is generated under rockburst test，true triaxial uniaxial compression test condition，respectively. The characteristics of particles distribution curves appear that it is gradual of rockburst test，steep of both true triaxial compression test and uniaxial compression test. Most micro-particles diameters of rockburst failure are smaller than of others. The particle diameter corresponding to the largest volume percentage value in the micro-particles distribution curves of rockburst are 40 and 60 μm. The particle diameters of true triaxial compression and uniaxial compression test are 80 and 100 μm respectively. The fractal dimension of micro-particles is calculated with the diameter-volume distribution. It implied that the micro-particles of rockburst failure fits the physics concept of statistics self-similar fractal rules，the others are not. More energy is dissipated during rockburst than that of true triaxial and uniaxial compression since a lot of micro-particles generated for rockburst sample.

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A ROCKBURST PRONENESS INDEX BASED ON
CLASS II WHOLE PROCESS CURVE

CAI Peng1，WU Aiqing1，WANG bin1，DENG Baohua2

2010, 29 (S1): -3294 doi:
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[PDF 207 KB] (979)

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Based on the energy storage and release properties that have been revealed by the class II whole process curve during rock failure process，and the rationality of several existing rockburst proneness indices，a new rockburst proneness index is proposed. The index borrows ideas from Wet of the ability of reflecting the relationship between elastic and plastic tendency of rock，and can reflect the energy transform character. At the same time，it also avoids the irrationality of index R of using the class I whole process curve of hard rock as calculation base. The mechanical tests of the rock from Jinping energy II power station auxiliary tunnel show that the new index is verified to be able to show fairly well the rockburst proneness of rock.

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EXPERIMENTAL STUDY OF SITE MONITORING OF ZIPINGPU TUNNEL WITH SMALL CLEAR SPACING

YAO Yong1，2，HE Chuan2，ZHANG Lingling1

2010, 29 (S1): -3300 doi:
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[PDF 278 KB] (844)

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For the purpose of saving construction cost，Wenchuan portal section of Zipingpu tunnel is so designed that twin tunnels in close proximity connected with Minjiang River bridge. On this portal section the spacing between right and left lines is small and the wall rock between them is weak. For the safety of tunnel construction，some monitoring tasks have been performed in Zipingpu tunnel，including the ground settlement，surrounding rocks pressure and internal force in lining，etc. Based on the measured data，it is shown that：(1) the influence of the later excavated tunnel on antecedence tunnel and the wall rock is existent in the construction of twin-bored tunnels，but the degree of influence is different. The surrounding rock is weaker，the extent of the influence is bigger. (2) The stress of the juncture section of the neighbor steps is relatively centralized，and the initial support is the most weak. The site monitoring is advised to adopted in the construction. (3) Because the wall rock is the most weak link in the construction of the small-distance tunnel，it is advised to take measures(such as the rational method of construction and site monitoring，etc.) to ensure the safety in the construction of Zipingpu tunnel.

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INVESTIGATION OF DYNAMIC RESPONSES FOR
DEEPLY-BURIED WIDE SPAN TUNNEL

ZHAO Yuetang1，FANG Changhai1，TIAN Xukun2

2010, 29 (S1): -3307 doi:
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[PDF 479 KB] (756)

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Taking an actual large underground engineering for example，the feasibility of simulating the multi-step excavating，shotcrete and rock bolt supporting for deeply buried wide span tunnel is investigated by using the explicit finite element method. Then，the dynamic responses are investigated under ground shock by nuclear contact surface burst. The analytical results make clear that the programs of excavation and supporting have a large influence on the final plastic strain state of tunnel and a small influence on the displacement state；in addition，the obvious upswell exists on the bottom floor of surrounding rock. For applied depth of burial，the increasing of plastic strain is negligible for applied loading in surrounding rock. It is worthy of note that the axial force of bolts increase to a considerable degree during ground shock；the supporting effect of bolts is necessary to increase the groundshock-resistant ability for deeply-buried wide span tunnel.

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EXPERIMENTAL RESEARCH ON MECHANICAL PROPERTIES OF LIMESTONE CONTAINING NATURAL JOINTS UNDER LOADING AND UNLOADING CONDITIONS

WANG Zaiquan，ZHANG Liming，SUN Hui

2010, 29 (S1): -3313 doi:
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[PDF 225 KB] (806)

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For the purpose of jointed rock mass excavation effect simulation，conventional triaxial test and stress control test of increasing axial pressure and unloading confining pressure of limestone containing natural joint have been performed；and the complete stress-strain curves were gained. The analytical results of fracture features of rocks，strength and deformation characteristics show that failure modes of the specimens can be classified into two types；one is shearing failure across the joint plane and the other is sliding failure along the joint plane whether the conventional triaxial test is or the stress control test of increasing axial pressure is. Conventional triaxial test shows that the specimen is shearing failure across the joint plane when the angle between the joint plane and the maximum principal stress is less than 40°；and the specimen is sliding failure along the joint plane when the angle is greater than 40°. But above two failure modes of loading and unloading test is not interrelated to the angle between the joint plane and the maximum principal stress. The peak strength，strength of sliding failure along the joint plane obviously less than that of shearing failure across the joint plane under loading and unloading condition. The failure specimens of sliding failure along the joint plane have not obvious yield stage；and the strength suddenly decreases after the peak strength；the yield and strength increase process don¢t exist compared to conventional triaxial test.

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DISPERSION EFFECT OF ELASTIC WAVE IN JOINTED BASALTS

LIU Yonggui1，XU Songlin1，XI Daoying2，LI Guangchang3，ZHENG Wen1，DENG Xiangyun1

2010, 29 (S1): -3320 doi:
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[PDF 334 KB] (2087)

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The jointed basalt is a kind of complicated material with large numbers of complex structures such as micro-cracks，micro-holes at the meso scale，and with non-uniformity and non-continuity properties at the macro scale，which leads to complexity of propagation rules of elastic wave in them. The analytical method based on the continuity can not be used to fully deal with those. In the present paper，for the study of mesostructure of rock on the law of wave propagation，cracks are taken for example and treated as inner boundaries. Based on the Green's function method，considering the introduction of suitable inner boundary conditions，and combined with method of boundary integral，the scattering of elastic wave is studied. Wave velocities of elastic wave predicted by the dispersion equation are compared to the results of laboratory experimental and in-situ test results，which show that the theoretical results in the present model are consistent well with in-situ test results；however，there is a wide gap with the results of laboratory experiment，which may be due to the differences between the environment of indoor experiment and in-situ test such as the stress state of rock samples，temperature and other factors. Furthermore，the mesostructures factors of the jointed basalt influencing on the dispersion effect are discussed，which results that the dispersion effect is strengthened with the increase in porosity and crack length in a certain range；all those results are guidance for in-situ test of acoustic and seismic wave.

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DYNAMIC STABILITY ANALYSIS AND SITE MONITORING OF REINFORCED HIGH ROCKFILL EMBANKMENT DURING CONSTRUCTION

YANG Chengzhong1，2，LIU Xinrong1，WANG Shufang2，FANG Tao1，2

2010, 29 (S1): -3328 doi:
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[PDF 308 KB] (827)

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To reveal the dynamic stability of high rockfill embankment with 72 m height on steep slope and provide reference for its quality control，By analyzing the rupture modulus of high embankment on steep slope and treatment measures for foundation，potential slipping circular arc of high rockfill embankment during construction is proposed. By analyzing the interaction between soil and reinforcement and references about previous triaxial test result，the mechanism that Geogrid improves the stability of embankment is expounded. Based on Sweden arc method of limit equilibrium theory，considering the filling process as 72 steps，the character of potential slipping circular arc at different layers are analyzed；the most dangerous sliding surface position is searched out；and the corresponding minimal safety factors are calculated. The results show that：With the increase of embankment¢s filled height，the potential slipping circulars moved to embankment body and its bottom. With the increasing of embankment¢s filled height and the surface slope，the minimal safety factors gradually decreased and the minimal safety factors occurred in the top layer；the overall stability meets the requirement of the specifications. Influenced by steep slope terrain，the safety factor changes obviously during the height between 32–48 m. Therefore，in the process of filling，the filling height and the changes in terrain should be paid more attention to，and corresponding measures should be taken to control the stability by the monitoring results.

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PERFORMANCE OF FULLY ENCAPSULATED RESIN ROCK BOLT
IN LAMINATED ROOF STRATA OF LONGWALL ROADWAY

LU Tingkan1，DAI Yaohui2

2010, 29 (S1): -3335 doi:
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[PDF 234 KB] (791)

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The strain gauge instrumented bolts have been installed on the roof strata of a longwall roadway to evaluate the performance of a fully encapsulated bolt，in terms of the axial load，its distribution along the length of the bolt，and the bending moment of the bolt in different mining activities. The results indicate that during the heading development，the performance of roof bolts is dominated by the stress redistribution. After the stress settles，the load of the bolt varies with the time-dependent characteristics of the surrounding rock mass. During the longwall extraction，the load on the bolts increases with the face approaching；and degradation of bolt load can be detected，when the face is close to the bolt；it indicates that the bolt is no longer able to provide its full function – to prevent the deformation of roof strata，due to failure of grouting material. It is found that the maximum axial load and bending moment on the bolt are increased 36% and 54% before and after extraction respectively；it is clearly indicated the different effects of static and dynamic loading conditions. It is also noted that the maximum bending moment is mainly located in the interface of different roof layers，which intends to move horizontally. The fully encapsulated bolt demonstrates two basic functions for reinforcing layered roof；firstly，preventing vertical movement of roof layers in different horizons；and secondly，providing shear resistance to prevent lateral movement between the roof layers.

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PHOTO-ElASTIC EXPERIMENTAL AND FIELD MEASUREMENT STUDY OF GROUND PRESSURE OF SURROUNDING ROCK OF LARGE DIP ANGLE WORKING COALFACE

YIN Guangzhi1，2，LI Xiaoshuang1，GUO Wenbing3

2010, 29 (S1): -3343 doi:
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[PDF 256 KB] (922)

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Based on the large dip angle coal working face of WU9–0–22090 of Xiangshan mine of Pingdingshan Coal and Electricity Co.，Ltd.，the ground pressure distribution laws of surrounding rock is studied through photo-elastic stimulation experiment and field measurement after coal mining. The research results show that the angle has an important effect on the distribution of the stress and bearing pressure of surrounding rock after coal mining，the deformation behavior，destroy characteristic and moving laws of stope roof of large dip angle coal working face are different with usual inclined working coal face；and the distribution of prop loading，the weighting presentation degree and the weighting distance are all different along the inclination of stope，and the distribution of roof stress is high nonuniform and asymmetrical. The roof stress is apparently concentrated in the two sides protected pillars¢ corner of goaf；then the bearing pressure region is formatted；and the pressure relieved region in the goaf of coal working face is also generated. The stress of stope roof relieved and the stress of two sides protected pillars are high concentrated；the shear stress of the four corners of stope apparently increased. And the shear strain mainly appeared in the roof of the low part of coalface and the floor of the upper part of coalface；the bulk strain is mainly focused in the adjacent coal roof and the two sides protected pillars. The research results are of significance in coal mining and roof management and enhancement of Xiangshan and similar coal mines.

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DYNAMIC MECHANISM OF WATER INRUSH FROM FLOOR OF MINING FACE

HU Weiyue1，YIN Shangxian2

2010, 29 (S1): -3349 doi:
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[PDF 310 KB] (1124)

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Stress distribution and its change regulation in floor rock mass of mining face with mining progress are analyzed in theory and the theory analysis results are proved by vertical stress in roof and floor of mining face which are measured and detected in boreholes with mining process. The change regulation of rock permeability in floor of mining face are tested in boreholes with mining progress. The relationships among mining，rock stress and water inrush from floor of mining face are studied. It is understood that there is a 0–20 m distance tensile stress area in floor rock of mining face and this area process with mining progress. The permeability of rock mass in tensile stress area is much bigger than other parts and it is easier to induce water inrush from floor of mining face.

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EXPERIMENTAL STUDY OF MECHANICAL PROPERTIES OF OUTBURST COAL CONTAINING GAS UNDER TRIAXIAL COMPRESSION

LI Xiaoshuang1，YIN Guangzhi1，2，ZHAO Hongbao1，WANG Weizhong1，2，JING Xiaofei1

2010, 29 (S1): -3358 doi:
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[PDF 420 KB] (937)

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Based on the briquette specimens of the outburst coal #7 seam of typical coal and gas outburst mine-Datong-One mine of Songzao coal and electricity Co.，Ltd.，the experiment for studying the mechanical properties of the gas-outburst coal under different external stresses pressure are carried out by a self-developed triaxial permeameter and Daojing AG–250 rock mechanics servo-controlled testing machine in the paper. The experimental results show that the confining pressure has an enhancement and progress effect on the mechanical properties of outburst coal containing gas under fixed gas pressure，and the triaxial compressive strength，elastic modulus and peak strain are all monotone and linear increasing with the increasing of confining pressure. The gas pressure has a weak effect on the mechanical properties of outburst coal containing gas under fixed confining pressure，the triaxial compressive strength and elastic modulus are respectively linear and logarithm function monotone decreasing with the increasing of gas pressure，but the peak strain is monotone and linear increasing with the increasing of gas pressure. The effective-stress has an enhancement and progress effect on the mechanical properties of outburst coal containing gas，the triaxial compressive strength，elastic modulus and peak strain are all monotone and linear increasing the with the increasing of effective-stress. The experimental results are of significance in gas extraction and the prediction and estimation of coal and gas outburst with the influence of coal mining.

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COLLAPSE MECHANISM OF DANGER ROCK TRIGGERED BY EARTHQUAKE

HE Siming1，2，WU Yong1，2，LI Xinpo1，2

2010, 29 (S1): -3363 doi:
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[PDF 244 KB] (893)

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As one of the most serious secondary hazards induced by earthquake，the rock collapse aggravates the seismic damage and restricts the reconstruction greatly. However，there are less effective measures that can be used to diagnosis and treat it danger rocks just for its mechanism is not clear at present. Thus from the true structure of rock，based on the rock fracture mechanics，and taking energy method as a main way，the mechanism of input and dissipation of seismic energy on danger rocks is studied. Then by analyzing the condition and process of crack propagation，the instability mechanism of dangerous rock caused by seismic wave is studied clearly. Furthermore，the calculation formula for critical acceleration and propagation length are also suggested. At last，an example is given to prove the theory. The result shows the cracks on danger rock can propagate and develop under enough big seismic action，which result in the failure of danger rock and the collapse occasion at last.

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STUDY OF ENERGY ATTENUATION LAW OF BLAST-INDUCED
SEISMIC WAVE

LI Hongtao1，LU Wenbo2，SHU Daqiang2，YANG Xingguo1，YI Changping3

2010, 29 (S1): -3369 doi:
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[PDF 189 KB] (1074)

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The effect of blast-induced seismic on buildings can be considered as a transferred and transformed process of the energy. Considering the command of blasting vibration control，it is necessary to know the attenuation law of blast-induced seismic，in order to make relatively accurate estimate for the extent of the buildings affected by blasting vibration. Based on seismology theory，energy attenuation law of blast-induced seismic wave is studied. It turns out that the attenuation coefficient for the peak energy is of twice that for the peak particle velocity(PPV). During a same blasting，the total energy of blast-induced seismic is of direct proportion with square of the peak particle velocity. Example analysis shows that theoretical derivation is correct，and energy of blast-induced seismic wave decays very quickly with the increase of the distance. Attenuation charismatic characteristics of blast-induced seismic are different from the earthquake，so these difference must be paid special attention when the methods usually applied in earthquake engineering are employed to study the dynamic response characteristic of blast-induced seismic.

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DYNAMIC NONLINEAR RESPONSE OF A LARGE UNDERGROUND ROCK CAVERN SUBJECTED TO SEISMIC MOTION CONSIDERING WAVE PASSAGE EFFECT

ZHAO Baoyou1，2，MA Zhenyue2，LIANG Bing1，SONG Zhiqiang2，ZHANG Cunhui2

2010, 29 (S1): -3377 doi:
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[PDF 369 KB] (703)

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The main features for this kind of rock cavern in a hydraulic power station are high walls，large span and long axial-length，the axial length of this kind of underground rock cavern is mainly ranging from 300 to 400 m. In order to study the influence of wave passage effect on the dynamic non-linear response of underground rock cavern under uniform and wave-passage seismic excitation，separately，a great many 3D nonlinear finite element numerical simulations are conducted by considering three different amplitudes of seismic motions. The damaged plasticity model is adopted for the rock mass. Geometric nonlinearity is also considered in each simulation. For a given seismic motion with specified frequency-spectrum features，the results show that：(1) seismic response of the cavern mainly depends on the amplitude of the seismic motions；(2) As the amplitude of seismic motions is small(for example，the peak ground acceleration is less than 0.1 g). The wave passage effect has no negative impact on the underground cavern，and the wave passage effect can be ignored. (3) However，as the peak ground acceleration is greater than 0.2 g，the wave passage effect dramatically aggravates the failure of underground cavern，which indicates that the wave passage effect should be considered once the rock cavern is built in regions with highly seismic activity.

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CHARACTERISTICS OF RAILWAY DAMAGE DUE TO WENCHUAN EARTHQUAKE AND COUNTERMEASURE CONSIDERATIONS OF ENGINEERING SEISMIC DESIGN

ZHU Ying，WEI Yongxing

2010, 29 (S1): -3386 doi:
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[PDF 930 KB] (1836)

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Wenchuan Earthquake and its characteristics as well as main types and features of railway engineering damage are described in brief. Such issues as lifeline project，secondary geological hazards induced by earthquake，near-field effects of earthquake and engineering design in near-field region，revision of seismic design standards for railway engineering and research on key technology for seismic design of railway engineering are discussed. The following suggestions for further research work on railway engineering seismic design are put forward. Enough attention to lifeline project should be paid in railway network planning and engineering construction. For the railway engineering in high seismic intensity mountain area，significant attention must be devoted to integrated location of railway and overall design based on prevention and mitigation of collapse and landslide induced by earthquake，and the sections where large-scale collapse and landslide incurred by potential earthquake shall be evaded，meanwhile，the high slope cutting of subgrade shall be avoided instead of selection of engineering form in favor of earthquake disaster prevention and reduction. For the engineering located in high seismic intensity region or on seismic fault zone，the relevant engineering technical standards on how to reduce earthquake hazard and repair earthquake damage rapidly shall be studied. Revision of code for seismic design of railway engineering shall be started as soon as possible，in which the requirements of design standard and method for engineering in earthquake near-field，especially earthquake fault zone，as well as the principles of integrated location of railway and overall design based on precaution and reduction of secondary seismic geologic hazard shall be added. The research on key technology for railway engineering seismic design in high seismic intensity mountain area，such as the integrated location of railway in high seismic intensity mountain area based on prevention and reduction of secondary geologic hazard and train operation control based on pre-earthquake forecast，etc.，is also recommended.

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RESEARCH ON FAILURE MODE OF ROAD EMBANKMENT IN WENCHUAN GREAT EARTHQUAKE AND DEFORMATION CONTROL OF GEOGRID REINFORCEMENT

WANG Jian1，YAO Lingkan1，CHEN Qiang2

2010, 29 (S1): -3394 doi:
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[PDF 718 KB] (900)

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To study the seismic design of subgrade engineering，subgrade seismic damage of Wenchuan Ms8.0 earthquake was investigated. It was found that most of the un-reinforced embankment suffered from shallow collapse of slope，of which a few were damaged by the sliding of embankment body，but neither of the embankment slid along the embankment-foundation interface. the damage level of geogrid-reinforced embankment was much slighter than that of un-reinforced embankment. Based on the investigation，the geogrid layout scheme was proposed to control the lateral deformation of embankment with long geogrid laid on the top of the embankment，and short geogrid laid on the upper part of the embankment. To validate this layout scheme，the un-reinforced and reinforced embankment were studied comparatively with large-scale shaking table model tests. Results showed that fissure spreading downward was restrained by long geogrid on the top of the embankment，thus deep slide prevented. Lateral deformation and shallow slide of the slope were restrained by short geogrid on the upper part of the embankment. By comparative analysis of acceleration and dynamic earth pressure between those two types of model test，it was found that when the road embankment was reinforced，natural frequency would increase by 12%，magnification factor of acceleration at 0.7 times the height of embankment would decrease by 27% under medium earthquake，decrease by 41% under large earthquake，and dynamic earth pressure would decrease largely also.

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SEISMIC RESPONSE OF A LARGE UNDERGROUND ROCK CAVERN GROUPS CONSIDERING DIFFERENT INCIDENT ANGLES OF EARTHQUAKE WAVES

ZHAO Baoyou1，2，MA Zhenyue2，DING Xiuli3

2010, 29 (S1): -3402 doi:
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[PDF 524 KB] (843)

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The finite-infinite element coupling model of a large underground rock cavern groups is set up which is located in the western of China. Firstly，in order to obtain the reasonable secondary geostress field，the rock cavern is excavated under the loading of gravity. Then its seismic response is studied under the combined loadings of the secondary geostress formed after excavation and the seismic motion considering different incident angles. Simulated results indicate that the obliquely incident earthquake waves dramatically influence the seismic response of underground rock cavern groups，for example，the distribution of stress and the plastic zone of the cavern groups. The incident angle of seismic wave should be taken into account in the seismic safety assessment of the similar underground rock cavern groups.

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FREE-FIELD STRESS AND GROUND MOTION OF UNDERGROUND CONFINED CHEMICAL EXPLOSIONS WITH SPHERICAL CHARGE IN LIMESTONE

WANG Zhanjiang，MEN Chaoju，LIU Guanlan，LI Yunliang，LI Xiaolan

2010, 29 (S1): -3410 doi:
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[PDF 326 KB] (713)

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According to the cube root scaling law，the test data of free-field stress(scale distance in 350 m/kt1/3)and ground motion(scale distance in 30 km/kt1/3) of a series of confined chemical explosion with spherical charges of 50，100，800，1 000，2 000 kgTNT in limestone have been analyzed，the attenuation of the free-field peak stress and the ground surface peak particle velocity，peak scaled particle displacement and peak scaled particle acceleration with scale distance are fitted，all the characteristic parameters are compared with that of nuclear explosion in hard rocks(granite，sandstone，limestone). The results show that，the ground surface peak scaled particle acceleration is far low in chemical explosions，and the others are principally in agreement with that of underground nuclear explosions. Some problems about in-situ measurements and data analysis are discussed，that mechanics effects of underground nuclear explosion could be to a certain extent simulated with underground chemical explosion is emphasized，and that a large number of on site data should be fitted statistically and it would be helpful in understanding the objective laws is also indicated. The instruments with higher frequency response must be provided in measuring free-field stress on underground chemical explosion. The higher frequency wave is attenuated quickly while propagating in rock mass，there are not distinct differences between ground motion frequencies of chemical explosion and nuclear explosion beyond a certain scale distance，acceleration is more sensitive to rock property on the travel path especially，which is the reason why the measured ground surface peak scaled particle acceleration is far low in chemical explosions.

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PROPAGATION ANALYSIS OF GROUND MOTION INDUCED BY EXPLOSION IN LOESS BASED ON WIGNER-
VILLE DISTRIBUTION

CAI Zongyi，WANG Zhanjiang，MEN Chaoju，LI Yunliang，WEN Chao，WU Zutang，CHEN Liqiang

2010, 29 (S1): -3416 doi:
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[PDF 236 KB] (1266)

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Seven underground explosion experiments that explosion equivalent is 100 kg TNT are carried out in the loess，and the ground motion signals are measured by four acceleration sensors laid in the range of 1 000 m away from the explosion source. By applying Wigner-Ville distribution to analysis the measured signals，the time-frequency characteristic parameters of the signals and its energy distribution are gained. The analysis shows that the ground motion signal in the loess is mainly composed of two center frequencies，respectively，in 4–10 and 11–16 Hz. The signal energy lies within 30 Hz，and the dominant frequency is in 8–15 Hz. According to the results，there are the obvious relations between the characteristic parameters¢ value of Wigner-Ville distribution of the ground motion signal and the distance away from the explosion source. Based on the analysis of the signals，as the distance away from the explosion source，it is found that the energy of the Wigner-Ville distribution¢s peak attenuates exponentially，the frequency corresponding to the Wigner-Ville distribution¢s peak reduces logarithmically，and the time corresponding to the Wigner-Ville distribution¢s peak increases linearly.

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INFLUENCE OF ACTIVATION FAULT AFTER COAL EXTRACTION ON COAL MINE KARST WATER -INRUSH

LI Qingfeng1，2，WANG Weijun1，2，PENG Wenqing1，2，PENG Gang1，2

2010, 29 (S1): -3424 doi:
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[PDF 401 KB] (904)

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For scientifically and effectively preventing karst water bursting because of fault activation，both the mining activation rule of fault and coal mine karst water bursting effect by fault activation are studied. First of all，according to the fault formation mechanism，the stress environment of all kinds of fault forming had been analyzed，and the stress condition of coal-seam fault activating had been discussed. Then，based on the law of stress field in stope and motion of the rock mass in the course of mining process，the main reason of fault activating is because of the uneven changes between secondary vertical stress and horizontal stress. Finally，it is analyzed that water-inrush mechanism of karst is initiated by activation of fault after coal extraction. Fault activation leads to the height of water flowing fractured zone increasing，and the karst aquifer is got through because aquifuge is failure，so water inrush accident is occurred.

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STUDY OF LAND SUBSIDENCE RULE OF DENSE BUILDINGS UNDER DIFFERENT FLOOR AREA RATIOS

TANG Yiqun1，2，SONG Shoupeng2，CHEN Bin2，WANG Jianxiu1，2，YANG Ping1，2

2010, 29 (S1): -3431 doi:
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With the development of city scale，engineering land subsidence caused by dense buildings has been paid more and more attention to. According to different floor area ratios，the rule of engineering land subsidence caused by dense buildings in soft soil area of Shanghai is discussed by means of centrifugal model test. Results show that the subsidence of soft soil layers is a main component of land subsidence. The subsidence variation with time of strata and regional points accords with exponential function. The superimposition effect of dense buildings on land subsidence is obvious and increases with the floor area ratios. In a certain floor area ratio，the superimposition effect of land subsidence has a significant time effect. The floor area ratio should be controlled in a certain extent to prevent land subsidence exceeding allowable value，which will cause instability of urban environment.

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SPATIAL MODELLING AND QUICK IDENTIFICATION OF UNSTABLE ROCK BLOCKS BASED ON DIGITAL PHOTOGRAMMETRY

WANG Shuhong，YANG Yong，WANG Yang，GUO Mudan，ZHANG Minsi

2010, 29 (S1): -3438 doi:
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The 3D modelling and the identification of unstable blocks are the crucially basic issues in jointed rock mass stability research. The deterministic structures of rock mass can be measured by adopting digital photogrammetry，and the model can be built by 3D structural network simulation，intersecting lines of surface structure and closed-loop analysis. A new block identification method is proposed：rock mass is divided into mesh and small block units are formed，then structure surfaces are added orderly to cut block into small units，after that mesh is removed and small block units are merged，finally a complex block is formed. An engineering example is analyzed based on this new identification method. The results show that the method is possessed of preferable generality and reliability，and it also could be used for advanced prediction and reinforcing scheme optimization in excavation process of rock tunnel.

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MODIFICATION OF ROCK SLOPE STABILITY CLASSIFICATION SYSTEMS BY CONTINUOUS FUNCTIONS AND ITS APPLICATIONS

LI Xiuzhen1，2，KONG Jiming1，2，WANG Chenghua1

2010, 29 (S1): -3446 doi:
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In order to decrease individual judgements caused by the discrete functions in the rock slope stability classification systems，the quantitative indexes of the systems，such as rock strength index(PLS or UCS)，rock quality designation index(RQD)，discontinuity spacing index(Js) and the correction factors of discontinuity direction，i.e. F1，F2 and F3，are systematically modified by continuous functions. The analytical results of 34 typical hydropower engineering rock slopes show that the values of the rock mass rating(RMR)，slope mass rating(SMR) and Chinese slope mass rating(CSMR) obtained by continuous functions agree well with the values obtained by origin discrete functions，and the correlation coefficients between them are 0.96，0.90 and 0.85，respectively. Moreover，there are stronger correlations between the values obtained by the modified functions and the factors of safety of the slopes. This verifies the rationality and reliability of the modification method. Thus，it can replace the origin method to effectively evaluate the stability of rock slope in practice.